Date | Change |
| 1784.11.26 | Apostolic Prefecture of United States of America was established (from Diocese of Québec and Apostolic Vicariate of London District) |
| 1789.11.06 | Apostolic Prefecture of United States of America was promoted as Diocese of Baltimore |
| 1793.04.25 | Diocese of Louisiana and the Two Floridas was established (from Diocese of La Habana) |
| 1808.04.08 | Diocese of Baltimore was promoted as Metropolitan Archdiocese of Baltimore (lost territory to establish Diocese of Boston, Diocese of New York, Diocese of Philadelphia and Diocese of Bardstown) |
| 1808.04.08 | Diocese of Bardstown was established (from Diocese of Baltimore) |
| 1808.04.08 | Diocese of Boston was established (from Diocese of Baltimore) |
| 1808.04.08 | Diocese of New York was established (from Diocese of Baltimore) |
| 1808.04.08 | Diocese of Philadelphia was established (from Diocese of Baltimore) |
| 1820.07.11 | Diocese of Charleston was established (from Metropolitan Archdiocese of Baltimore) |
| 1820.07.11 | Diocese of Richmond was established (from Metropolitan Archdiocese of Baltimore) |
| 1821.06.19 | Diocese of Cincinnati was established (from Diocese of Bardstown) |
| 1822.08.13 | Apostolic Vicariate of Mississippi and Alabama was established (from Diocese of Louisiana and the Two Floridas) |
| 1823.06.22 | Apostolic Vicariate of Mississippi and Alabama was suppressed (to Diocese of Louisiana and the Two Floridas) |
| 1825.08.29 | Apostolic Vicariate of Alabama and the Floridas was established (from Metropolitan Archdiocese of Baltimore and Diocese of Louisiana and the Two Floridas) |
| 1825.08.29 | Diocese of Louisiana and the Two Floridas was renamed as Diocese of Louisiana (lost territory to establish Apostolic Vicariate of Alabama and the Floridas) |
| 1825.10.24 | Apostolic Prefecture of Sandwich Islands was established |
| 1826.07.18 | Apostolic Vicariate of Mississippi was established (from Diocese of Louisiana) |
| 1826.07.18 | Diocese of Louisiana was renamed as Diocese of New Orleans (lost territory to establish Diocese of Saint Louis and Apostolic Vicariate of Mississippi) |
| 1826.07.18 | Diocese of Saint Louis was established (from Diocese of Durango and Diocese of Louisiana) |
| 1829.05.15 | Apostolic Vicariate of Alabama and the Floridas was promoted as Diocese of Mobile |
| 1833.03.08 | Diocese of Detroit was established (from Diocese of Cincinnati) |
| 1834.05.06 | Diocese of Vincennes was established (from Diocese of Bardstown) |
| 1837.07.28 | Diocese of Dubuque was established (from Diocese of Saint Louis) |
| 1837.07.28 | Diocese of Nashville was established (from Diocese of Bardstown) |
| 1837.07.28 | Apostolic Vicariate of Mississippi was promoted as Diocese of Natchez |
| 1839 | Apostolic Prefecture of Texas was established (from Diocese of Linares) |
| 1840.04.27 | Diocese of Two Californias was established (from Diocese of Sonora) |
| 1841.02.13 | Diocese of Bardstown was suppressed (to establish Diocese of Louisville) |
| 1841.02.13 | Diocese of Louisville was established (from the suppressed Diocese of Bardstown) |
| 1841.07.10 | Apostolic Prefecture of Texas was promoted as Apostolic Vicariate of Texas |
| 1843.08.11 | Diocese of Pittsburgh was established (from Diocese of Philadelphia) |
| 1843.11.28 | Diocese of Chicago was established (from Diocese of Saint Louis) |
| 1843.11.28 | Diocese of Hartford was established (from Diocese of Boston) |
| 1843.11.28 | Diocese of Little Rock was established (from Diocese of Saint Louis) |
| 1843.11.28 | Diocese of Milwaukee was established (from Diocese of Detroit) |
| 1843.12.01 | Apostolic Vicariate of Oregon was established (from Metropolitan Archdiocese of Baltimore and Archdiocese of Québec) |
| 1844 | Apostolic Prefecture of Sandwich Islands was promoted as Apostolic Vicariate of Sandwich Islands |
| 1846.07.24 | Apostolic Vicariate of Oregon was promoted as Diocese of Oregon City (lost territory to establish Diocese of Vancouver Island and Diocese of Walla Walla) |
| 1846.07.24 | Diocese of Walla Walla was established (from Apostolic Vicariate of Oregon) |
| 1847.04.23 | Diocese of Albany was established (from Diocese of New York) |
| 1847.04.23 | Diocese of Buffalo was established (from Diocese of New York) |
| 1847.04.23 | Diocese of Cleveland was established (from Diocese of Cincinnati) |
| 1847.05.04 | Apostolic Vicariate of Texas was promoted as Diocese of Galveston |
| 1847.07.11 | Apostolic Vicariate of Sandwich Islands was renamed as Apostolic Vicariate of Hawaiian Islands |
| 1847.07.20 | Diocese of Saint Louis was promoted as Metropolitan Archdiocese of Saint Louis |
| 1849.11.20 | Diocese of Two Californias was renamed as Diocese of Monterey |
| 1850.05.31 | Diocese of Nesqually was established (from Diocese of Walla Walla) |
| 1850.07.03 | Diocese of Savannah was established (from Diocese of Mobile and Diocese of Charleston) |
| 1850.07.19 | Diocese of Cincinnati was promoted as Metropolitan Archdiocese of Cincinnati |
| 1850.07.19 | Apostolic Vicariate of Indian Territory East of the Rocky Mountains was established (from Diocese of New Orleans) |
| 1850.07.19 | Diocese of New Orleans was promoted as Metropolitan Archdiocese of New Orleans (lost territory to establish Apostolic Vicariate of Indian Territory East of the Rocky Mountains) |
| 1850.07.19 | Diocese of New York was promoted as Metropolitan Archdiocese of New York |
| 1850.07.19 | Diocese of Saint Paul was established (from Diocese of Dubuque and Diocese of Milwaukee) |
| 1850.07.19 | Diocese of Wheeling was established (from Diocese of Richmond) |
| 1850.07.23 | Apostolic Vicariate of New Mexico was established (from Diocese of Durango) |
| 1850.07.29 | Diocese of Oregon City was promoted as Metropolitan Archdiocese of Oregon City |
| 1853.07.29 | Diocese of Brooklyn was established (from Metropolitan Archdiocese of New York) |
| 1853.07.29 | Diocese of Burlington was established (from Diocese of Boston) |
| 1853.07.29 | Diocese of Covington was established (from Diocese of Louisville) |
| 1853.07.29 | Diocese of Erie was established (from Diocese of Pittsburgh) |
| 1853.07.29 | Diocese of Natchitoches was established (from Metropolitan Archdiocese of New Orleans) |
| 1853.07.29 | Diocese of Newark was established (from Metropolitan Archdiocese of New York and Diocese of Philadelphia) |
| 1853.07.29 | Diocese of Portland in Maine was established (from Diocese of Boston) |
| 1853.07.29 | Diocese of Quincy was established (from Diocese of Chicago) |
| 1853.07.29 | Metropolitan Archdiocese of San Francisco was established (from Diocese of Monterey) |
| 1853.07.29 | Apostolic Vicariate of New Mexico was promoted as Diocese of Santa Fe |
| 1853.07.29 | Apostolic Vicariate of Upper Michigan was established (from Diocese of Detroit) |
| 1853.07.29 | Diocese of Walla Walla was suppressed (to Diocese of Nesqually) |
| 1857 | Apostolic Vicariate of Indian Territory East of the Rocky Mountains was renamed as Apostolic Vicariate of Kansas |
| 1857.01.06 | Apostolic Vicariate of Nebraska was established (from Apostolic Vicariate of Indian Territory East of the Rocky Mountains) |
| 1857.01.08 | Diocese of Fort Wayne was established (from Diocese of Vincennes) |
| 1857.01.09 | Diocese of Alton was established (from the suppressed Diocese of Quincy) |
| 1857.01.09 | Apostolic Vicariate of Florida was established (from Diocese of Savannah) |
| 1857.01.09 | Diocese of Quincy was suppressed (to establish Diocese of Alton) |
| 1857.01.09 | Apostolic Vicariate of Upper Michigan was promoted as Diocese of Sault Sainte Marie |
| 1859.07.07 | Diocese of Monterey was renamed as Diocese of Monterey–Los Angeles |
| 1860.09.27 | Apostolic Vicariate of Marysville was established (from Metropolitan Archdiocese of San Francisco) |
| 1865.10.23 | Diocese of Sault Sainte Marie was renamed as Diocese of Sault Sainte Marie–Marquette |
| 1868 | Apostolic Vicariate of Arizona was established (from Diocese of Santa Fe) |
| 1868 | Apostolic Vicariate of Colorado and Utah was established (from Diocese of Santa Fe) |
| 1868.03.03 | Diocese of Columbus was established (from Metropolitan Archdiocese of Cincinnati) |
| 1868.03.03 | Diocese of Green Bay was established (from Diocese of Milwaukee) |
| 1868.03.03 | Diocese of Harrisburg was established (from Diocese of Philadelphia) |
| 1868.03.03 | Apostolic Vicariate of Idaho and Montana was established (from Metropolitan Archdiocese of Oregon City) |
| 1868.03.03 | Diocese of La Crosse was established (from Diocese of Milwaukee) |
| 1868.03.03 | Apostolic Vicariate of North Carolina was established (from Diocese of Charleston) |
| 1868.03.03 | Diocese of Rochester was established (from Diocese of Buffalo) |
| 1868.03.03 | Diocese of Saint Joseph was established (from Metropolitan Archdiocese of Saint Louis) |
| 1868.03.03 | Diocese of Scranton was established (from Diocese of Philadelphia) |
| 1868.03.03 | Diocese of Wilmington was established (from Metropolitan Archdiocese of Baltimore and Diocese of Philadelphia) |
| 1868.03.22 | Apostolic Vicariate of Marysville was promoted as Diocese of Grass Valley |
| 1870 | Apostolic Vicariate of Colorado and Utah was renamed as Apostolic Vicariate of Colorado |
| 1870.03.11 | Apostolic Vicariate of Florida was promoted as Diocese of Saint Augustine |
| 1870.06.14 | Diocese of Springfield in Massachusetts was established (from Diocese of Boston) |
| 1872.02.15 | Diocese of Ogdensburg was established (from Diocese of Albany) |
| 1872.02.16 | Diocese of Providence was established (from Diocese of Boston and Diocese of Hartford) |
| 1874.08.28 | Apostolic Vicariate of Brownsville was established (from Diocese of Galveston) |
| 1874.08.28 | Diocese of San Antonio was established (from Diocese of Galveston) |
| 1875.02.12 | Diocese of Boston was promoted as Metropolitan Archdiocese of Boston |
| 1875.02.12 | Diocese of Milwaukee was promoted as Metropolitan Archdiocese of Milwaukee |
| 1875.02.12 | Apostolic Vicariate of Northern Minnesota was established (from Diocese of Saint Paul) |
| 1875.02.12 | Diocese of Peoria was established (from Diocese of Chicago) |
| 1875.02.12 | Diocese of Philadelphia was promoted as Metropolitan Archdiocese of Philadelphia |
| 1875.02.12 | Diocese of Santa Fe was promoted as Metropolitan Archdiocese of Santa Fe |
| 1876.01.11 | Diocese of Allegheny was established (from Diocese of Pittsburgh) |
| 1876.05.14 | Apostolic Prefecture of Indian Territory was established (from Diocese of Little Rock) |
| 1877.05.22 | Apostolic Vicariate of Kansas was promoted as Diocese of Leavenworth |
| 1879.08.12 | Apostolic Vicariate of Dakota was established (from Diocese of Saint Paul) |
| 1880.09.10 | Diocese of Chicago was promoted as Metropolitan Archdiocese of Chicago |
| 1880.09.10 | Diocese of Kansas City was established (from Metropolitan Archdiocese of Saint Louis) |
| 1881.06.14 | Diocese of Davenport was established (from Diocese of Dubuque) |
| 1881.08.02 | Diocese of Trenton was established (from Diocese of Newark) |
| 1882.05.19 | Diocese of Grand Rapids was established (from Diocese of Detroit) |
| 1883.03.05 | Apostolic Vicariate of Idaho and Montana was renamed as Apostolic Vicariate of Idaho (lost territory to establish Apostolic Vicariate of Montana) |
| 1883.03.05 | Apostolic Vicariate of Montana was established (from Apostolic Vicariate of Idaho and Montana) |
| 1884.03.07 | Apostolic Vicariate of Montana was promoted as Diocese of Helena |
| 1884.04.15 | Diocese of Manchester was established (from Diocese of Portland in Maine) |
| 1885.10.02 | Apostolic Vicariate of Nebraska was promoted as Diocese of Omaha |
| 1886.05.28 | Diocese of Grass Valley was suppressed (to establish Diocese of Sacramento) |
| 1886.05.28 | Diocese of Sacramento was established (from Metropolitan Archdiocese of San Francisco, and from the suppressed Diocese of Grass Valley) |
| 1886.11.26 | Diocese of Syracuse was established (from Diocese of Albany) |
| 1887 | Apostolic Vicariate of Utah was established (from Metropolitan Archdiocese of San Francisco) |
| 1887.01.07 | Diocese of Belleville was established (from Diocese of Alton) |
| 1887.08.02 | Diocese of Cheyenne was established (from Diocese of Omaha) |
| 1887.08.02 | Diocese of Concordia was established (from Diocese of Leavenworth) |
| 1887.08.02 | Diocese of Lincoln was established (from Diocese of Omaha) |
| 1887.08.02 | Diocese of Wichita was established (from Diocese of Leavenworth) |
| 1887.08.16 | Apostolic Vicariate of Colorado was promoted as Diocese of Denver |
| 1888.05.04 | Diocese of Saint Paul was promoted as Metropolitan Archdiocese of Saint Paul |
| 1889.07.01 | Diocese of Allegheny was suppressed (to Diocese of Pittsburgh) |
| 1889.09.22 | Apostolic Vicariate of Northern Minnesota was promoted as Diocese of Saint Cloud |
| 1889.10.03 | Diocese of Duluth was established (from Diocese of Saint Cloud) |
| 1889.11.10 | Diocese of Jamestown was established (from Apostolic Vicariate of Dakota) |
| 1889.11.12 | Apostolic Vicariate of Dakota was promoted as Diocese of Sioux Falls |
| 1889.11.26 | Diocese of Winona was established (from Metropolitan Archdiocese of Saint Paul) |
| 1890.07.15 | Diocese of Dallas was established (from Diocese of Galveston) |
| 1891.01.27 | Apostolic Vicariate of Utah was promoted as Diocese of Salt Lake |
| 1891.05.29 | Apostolic Prefecture of Indian Territory was promoted as Apostolic Vicariate of Indian Territory |
| 1891.05.29 | Diocese of Leavenworth was renamed as Diocese of Kansas City, Kansas |
| 1893.06.15 | Diocese of Dubuque was promoted as Metropolitan Archdiocese of Dubuque |
| 1893.08.25 | Apostolic Vicariate of Idaho was promoted as Diocese of Boise City |
| 1894.07.27 | Apostolic Prefecture of Alaska was established (from Diocese of New Westminster and Diocese of Vancouver Island) |
| 1897.03.05 | Diocese of Kansas City, Kansas was renamed as Diocese of Leavenworth |
| 1897.04.06 | Diocese of Fargo was established (from the suppressed Diocese of Jamestown) |
| 1897.04.06 | Diocese of Jamestown was suppressed (to establish Diocese of Fargo) |
| 1897.05.08 | Apostolic Vicariate of Arizona was promoted as Diocese of Tucson |
| 1898.03.28 | Diocese of Indianapolis was established (from the suppressed Diocese of Vincennes) |
| 1898.03.28 | Diocese of Vincennes was suppressed (to establish Diocese of Indianapolis) |
| 1901.05.30 | Diocese of Altoona was established (from Diocese of Harrisburg and Diocese of Pittsburgh) |
| 1902.01.15 | Diocese of Sioux City was established (from Metropolitan Archdiocese of Dubuque) |
| 1902.08.04 | Diocese of Lead was established (from Diocese of Sioux Falls) |
| 1903.06.19 | Diocese of Baker City was established (from Metropolitan Archdiocese of Oregon City) |
| 1904.03.12 | Diocese of Fall River was established (from Diocese of Providence) |
| 1904.05.18 | Diocese of Great Falls was established (from Diocese of Helena) |
| 1905.05.03 | Diocese of Superior was established (from Diocese of Green Bay and Diocese of La Crosse) |
| 1905.08.23 | Apostolic Vicariate of Indian Territory was promoted as Diocese of Oklahoma |
| 1907.09.11 | Diocese of Nesqually was suppressed (to establish Diocese of Seattle) |
| 1907.09.11 | Diocese of Seattle was established (from the suppressed Diocese of Nesqually) |
| 1908.09.27 | Diocese of Rockford was established (from Metropolitan Archdiocese of Chicago) |
| 1909.12.31 | Diocese of Bismarck was established (from Diocese of Fargo) |
| 1909.12.31 | Diocese of Crookston was established (from Metropolitan Archdiocese of Saint Paul) |
| 1910.04.15 | Diocese of Toledo was established (from Diocese of Cleveland) |
| 1910.06.08 | Territorial Abbacy of Belmont–Mary Help of Christians was established (from Apostolic Vicariate of North Carolina) |
| 1910.08.06 | Diocese of Alexandria was established (from the suppressed Diocese of Natchitoches) |
| 1910.08.06 | Diocese of Natchitoches was suppressed (to establish Diocese of Alexandria) |
| 1911.08.12 | Diocese of Des Moines was established (from Diocese of Davenport) |
| 1912.03.08 | Diocese of Kearney was established (from Diocese of Omaha) |
| 1912.03.23 | Apostolic Vicariate of Brownsville was suppressed (to establish Diocese of Corpus Christi) |
| 1912.03.23 | Diocese of Corpus Christi was established (from the suppressed Apostolic Vicariate of Brownsville) |
| 1913.05.28 | Ordinariate of United States of America (Ukrainian Rite) was established |
| 1913.12.17 | Diocese of Spokane was established (from Diocese of Seattle) |
| 1914.03.03 | Diocese of El Paso was established (from Diocese of San Antonio, Diocese of Dallas and Diocese of Tucson) |
| 1917.02.15 | Apostolic Prefecture of Alaska was promoted as Apostolic Vicariate of Alaska |
| 1917.04.11 | Diocese of Grand Island was established (from the suppressed Diocese of Kearney) |
| 1917.04.11 | Diocese of Kearney was suppressed (to establish Diocese of Grand Island) |
| 1918.01.11 | Diocese of Lafayette in Louisiana was established (from Metropolitan Archdiocese of New Orleans) |
| 1922.06.01 | Diocese of Los Angeles–San Diego was established (from Diocese of Monterey–Los Angeles) |
| 1922.06.01 | Diocese of Monterey–Los Angeles was renamed as Diocese of Monterey–Fresno (lost territory to establish Diocese of Los Angeles–San Diego) |
| 1923.10.26 | Diocese of Alton was suppressed (to establish Diocese of Springfield in Illinois) |
| 1923.10.26 | Diocese of Springfield in Illinois was established (from the suppressed Diocese of Alton) |
| 1924.05.08 | Apostolic Exarchate of United States of America (Ruthenian Rite) was established |
| 1924.05.08 | Ordinariate of United States of America (Ukrainian Rite) was promoted as Apostolic Exarchate of United States of America |
| 1924.12.12 | Apostolic Vicariate of North Carolina was promoted as Diocese of Raleigh |
| 1926.08.03 | Diocese of Amarillo was established (from Diocese of San Antonio and Diocese of Dallas) |
| 1926.08.03 | Diocese of San Antonio was promoted as Metropolitan Archdiocese of San Antonio (lost territory to establish Diocese of Amarillo) |
| 1928.09.26 | Metropolitan Archdiocese of Oregon City was suppressed (to establish Metropolitan Archdiocese of Portland in Oregon) |
| 1928.09.26 | Metropolitan Archdiocese of Portland in Oregon was established (from the suppressed Metropolitan Archdiocese of Oregon City) |
| 1930.08.01 | Diocese of Lead was suppressed (to establish Diocese of Rapid City) |
| 1930.08.01 | Diocese of Rapid City was established (from the suppressed Diocese of Lead) |
| 1930.11.14 | Diocese of Oklahoma was renamed as Diocese of Oklahoma City–Tulsa |
| 1931.03.27 | Diocese of Reno was established (from Diocese of Sacramento and Diocese of Salt Lake) |
| 1936.07.11 | Diocese of Los Angeles–San Diego was promoted as Metropolitan Archdiocese of Los Angeles (lost territory to establish Diocese of San Diego) |
| 1936.07.11 | Diocese of San Diego was established (from Diocese of Los Angeles–San Diego) |
| 1937.01.03 | Diocese of Marquette was established (from the suppressed Diocese of Sault Sainte Marie–Marquette) |
| 1937.01.03 | Diocese of Sault Sainte Marie–Marquette was suppressed (to establish Diocese of Marquette) |
| 1937.01.05 | Diocese of Savannah was renamed as Diocese of Savannah–Atlanta |
| 1937.05.22 | Diocese of Detroit was promoted as Metropolitan Archdiocese of Detroit (lost territory to establish Diocese of Lansing) |
| 1937.05.22 | Diocese of Lansing was established (from Diocese of Detroit) |
| 1937.12.09 | Diocese of Camden was established (from Diocese of Trenton) |
| 1937.12.09 | Diocese of Owensboro was established (from Diocese of Louisville) |
| 1937.12.09 | Diocese of Paterson was established (from Diocese of Newark) |
| 1937.12.10 | Diocese of Louisville was promoted as Metropolitan Archdiocese of Louisville |
| 1937.12.10 | Diocese of Newark was promoted as Metropolitan Archdiocese of Newark |
| 1938.02.26 | Diocese of Saginaw was established (from Metropolitan Archdiocese of Detroit and Diocese of Grand Rapids) |
| 1939.07.22 | Metropolitan Archdiocese of Baltimore was renamed as Metropolitan Archdiocese of Baltimore–Washington |
| 1939.11 | Military Vicariate of United States of America was established |
| 1939.12.16 | Diocese of Gallup was established (from Metropolitan Archdiocese of Santa Fe and Diocese of Tucson) |
| 1941.01.25 | Apostolic Vicariate of Hawaiian Islands was promoted as Diocese of Honolulu |
| 1941.11.15 | Diocese of Denver was promoted as Metropolitan Archdiocese of Denver (lost territory to establish Diocese of Pueblo) |
| 1941.11.15 | Diocese of Pueblo was established (from Diocese of Denver) |
| 1943.05.15 | Diocese of Youngstown was established (from Diocese of Cleveland) |
| 1944.10.21 | Diocese of Evansville was established (from Diocese of Indianapolis) |
| 1944.10.21 | Diocese of Indianapolis was promoted as Metropolitan Archdiocese of Indianapolis (lost territory to establish Diocese of Evansville) |
| 1944.10.21 | Diocese of Lafayette in Indiana was established (from Diocese of Fort Wayne) |
| 1944.10.21 | Diocese of Steubenville was established (from Diocese of Columbus) |
| 1944.12.23 | Diocese of Concordia was suppressed (to establish Diocese of Salina) |
| 1944.12.23 | Diocese of Salina was established (from the suppressed Diocese of Concordia) |
| 1945.08.04 | Diocese of Omaha was promoted as Metropolitan Archdiocese of Omaha |
| 1945.12.22 | Diocese of Madison was established (from Metropolitan Archdiocese of Milwaukee, Diocese of Green Bay and Diocese of La Crosse) |
| 1947.05.10 | Diocese of Kansas City was established (from the suppressed Diocese of Leavenworth) |
| 1947.05.10 | Diocese of Leavenworth was suppressed (to establish Diocese of Kansas City) |
| 1947.11.15 | Diocese of Austin was established (from Diocese of Galveston, Metropolitan Archdiocese of San Antonio and Diocese of Dallas) |
| 1947.11.15 | Metropolitan Archdiocese of Baltimore–Washington was renamed as Metropolitan Archdiocese of Baltimore (lost territory to establish Archdiocese of Washington) |
| 1947.11.15 | Archdiocese of Washington was established (from Metropolitan Archdiocese of Baltimore–Washington) |
| 1948.12.11 | Diocese of Joliet was established (from Metropolitan Archdiocese of Chicago, Diocese of Peoria and Diocese of Rockford) |
| 1950.01.14 | Diocese of Worcester was established (from Diocese of Springfield in Massachusetts) |
| 1951.03.10 | Diocese of Greensburg was established (from Diocese of Pittsburgh) |
| 1951.03.31 | Diocese of Salt Lake was renamed as Diocese of Salt Lake City |
| 1951.05.19 | Diocese of Dodge City was established (from Diocese of Wichita) |
| 1951.06.23 | Diocese of Juneau was established (from Apostolic Vicariate of Alaska) |
| 1951.06.23 | Diocese of Seattle was promoted as Metropolitan Archdiocese of Seattle (lost territory to establish Diocese of Yakima) |
| 1951.06.23 | Diocese of Yakima was established (from Diocese of Seattle and Diocese of Spokane) |
| 1952.02.16 | Diocese of Baker City was renamed as Diocese of Baker |
| 1952.08.09 | Diocese of Kansas City was promoted as Metropolitan Archdiocese of Kansas City |
| 1953.08.06 | Diocese of Bridgeport was established (from Diocese of Hartford) |
| 1953.08.06 | Diocese of Hartford was promoted as Metropolitan Archdiocese of Hartford (lost territory to establish Diocese of Bridgeport and Diocese of Norwich) |
| 1953.08.06 | Diocese of Norwich was established (from Diocese of Hartford) |
| 1953.10.20 | Diocese of Dallas was renamed as Diocese of Dallas–Fort Worth |
| 1954.04.30 | Diocese of Mobile was renamed as Diocese of Mobile–Birmingham |
| 1956.07.02 | Diocese of Atlanta was established (from Diocese of Savannah–Atlanta) |
| 1956.07.02 | Diocese of Jefferson City was established (from Metropolitan Archdiocese of Saint Louis and Diocese of Kansas City, and from the suppressed Diocese of Saint Joseph) |
| 1956.07.02 | Diocese of Kansas City was renamed as Diocese of Kansas City–Saint Joseph (gained territory from the suppressed Diocese of Saint Joseph, and lost territory to establish Diocese of Jefferson City and Diocese of Springfield–Cape Girardeau) |
| 1956.07.02 | Diocese of Saint Joseph was suppressed (to Diocese of Kansas City–Saint Joseph, and to establish Diocese of Jefferson City and Diocese of Springfield–Cape Girardeau) |
| 1956.07.02 | Diocese of Savannah–Atlanta was renamed as Diocese of Savannah (lost territory to establish Diocese of Atlanta) |
| 1956.07.02 | Diocese of Springfield–Cape Girardeau was established (from Metropolitan Archdiocese of Saint Louis and Diocese of Kansas City, and from the suppressed Diocese of Saint Joseph) |
| 1956.07.20 | Apostolic Exarchate of Stamford (Ukrainian Rite) was established (from Apostolic Exarchate of United States of America) |
| 1956.12.10 | Diocese of Gary was established (from Diocese of Fort Wayne) |
| 1956.12.18 | Diocese of Natchez was renamed as Diocese of Natchez–Jackson |
| 1957.04.06 | Diocese of Rockville Centre was established (from Diocese of Brooklyn) |
| 1957.10.09 | Diocese of Altoona was renamed as Diocese of Altoona–Johnstown |
| 1957.11.18 | Diocese of New Ulm was established (from Metropolitan Archdiocese of Saint Paul) |
| 1958.05.25 | Diocese of Miami was established (from Diocese of Saint Augustine) |
| 1958.07.10 | Apostolic Exarchate of United States of America (Ukrainian Rite) was promoted as Metropolitan Archdiocese of Philadelphia |
| 1958.07.10 | Apostolic Exarchate of Stamford (Ukrainian Rite) was promoted as Diocese of Stamford |
| 1959.07.25 | Diocese of Galveston was renamed as Diocese of Galveston–Houston |
| 1960.05.28 | Diocese of Fort Wayne was renamed as Diocese of Fort Wayne–South Bend |
| 1961.01.28 | Diocese of Allentown was established (from Metropolitan Archdiocese of Philadelphia) |
| 1961.07.14 | Diocese of Saint Nicholas of Chicago (Ukrainian Rite) was established (from Metropolitan Archdiocese of Philadelphia) |
| 1961.07.22 | Diocese of Baton Rouge was established (from Metropolitan Archdiocese of New Orleans) |
| 1961.10.16 | Diocese of San Angelo was established (from Diocese of Amarillo, Diocese of Austin and Diocese of Dallas–Fort Worth) |
| 1962.01.13 | Diocese of Oakland was established (from Metropolitan Archdiocese of San Francisco) |
| 1962.01.13 | Diocese of Santa Rosa was established (from Metropolitan Archdiocese of San Francisco) |
| 1962.01.13 | Diocese of Stockton was established (from Metropolitan Archdiocese of San Francisco and Diocese of Sacramento) |
| 1962.02.10 | Diocese of Atlanta was promoted as Metropolitan Archdiocese of Atlanta |
| 1962.08.08 | Apostolic Vicariate of Alaska was promoted as Diocese of Fairbanks |
| 1963.07.06 | Diocese of Passaic (Ruthenian Rite) was established (from Apostolic Exarchate of United States of America) |
| 1963.07.06 | Apostolic Exarchate of United States of America (Ruthenian Rite) was promoted as Diocese of Pittsburgh (lost territory to establish Diocese of Passaic) |
| 1965.07.10 | Diocese of Brownsville was restored (from Diocese of Corpus Christi) |
| 1965.10.12 | Archdiocese of Washington was promoted as Metropolitan Archdiocese of Washington |
| 1966.01.10 | Apostolic Exarchate of United States of America (Maronite Rite) was established |
| 1966.01.10 | Apostolic Exarchate of United States of America (Greek-Melkite Rite) was established |
| 1966.01.22 | Metropolitan Archdiocese of Anchorage was established (from Diocese of Juneau) |
| 1966.06.25 | Diocese of Beaumont was established (from Diocese of Galveston–Houston) |
| 1966.07.11 | Metropolitan Archdiocese of Saint Paul was renamed as Metropolitan Archdiocese of Saint Paul and Minneapolis |
| 1967.10.06 | Diocese of Fresno was established (from Diocese of Monterey–Fresno) |
| 1967.10.06 | Diocese of Monterey–Fresno was renamed as Diocese of Monterey (lost territory to establish Diocese of Fresno) |
| 1968.03.02 | Diocese of Miami was promoted as Metropolitan Archdiocese of Miami (lost territory to establish Diocese of Orlando and Diocese of Saint Petersburg) |
| 1968.03.02 | Diocese of Orlando was established (from Diocese of Miami and Diocese of Saint Augustine) |
| 1968.03.02 | Diocese of Saint Petersburg was established (from Diocese of Miami and Diocese of Saint Augustine) |
| 1969.02.21 | Diocese of Pittsburgh (Ruthenian Rite) was promoted as Metropolitan Archdiocese of Munhall (lost territory to establish Diocese of Parma) |
| 1969.02.21 | Diocese of Parma (Ruthenian Rite) was established (from Diocese of Pittsburgh) |
| 1969.06.28 | Diocese of Birmingham was established (from Diocese of Mobile–Birmingham) |
| 1969.06.28 | Diocese of Mobile–Birmingham was renamed as Diocese of Mobile (lost territory to establish Diocese of Birmingham) |
| 1969.06.28 | Diocese of Phoenix was established (from Diocese of Tucson) |
| 1969.08.09 | Diocese of Dallas–Fort Worth was renamed as Diocese of Dallas (lost territory to establish Diocese of Fort Worth) |
| 1969.08.09 | Diocese of Fort Worth was established (from Diocese of Dallas–Fort Worth) |
| 1970.06.20 | Diocese of Memphis was established (from Diocese of Nashville) |
| 1970.12.19 | Diocese of Gaylord was established (from Diocese of Grand Rapids and Diocese of Saginaw) |
| 1970.12.19 | Diocese of Kalamazoo was established (from Diocese of Grand Rapids and Diocese of Lansing) |
| 1971 | Titular Episcopal See of Allegheny was restored |
| 1971 | Titular Episcopal See of Walla Walla was restored |
| 1971.11.12 | Diocese of Charlotte was established (from Diocese of Raleigh) |
| 1971.11.29 | Apostolic Exarchate of United States of America (Maronite Rite) was promoted as Diocese of Saint Maron of Detroit |
| 1972.12.13 | Diocese of Oklahoma City–Tulsa was promoted as Metropolitan Archdiocese of Oklahoma City (lost territory to establish Diocese of Tulsa) |
| 1972.12.13 | Diocese of Tulsa was established (from Diocese of Oklahoma City–Tulsa) |
| 1974.05.28 | Diocese of Arlington was established (from Metropolitan Archdiocese of Washington and Diocese of Richmond) |
| 1974.08.21 | Diocese of Wheeling was renamed as Diocese of Wheeling–Charleston |
| 1975.10.01 | Diocese of Pensacola–Tallahassee was established (from Diocese of Mobile and Diocese of Saint Augustine) |
| 1976.03.24 | Diocese of Orange was established (from Metropolitan Archdiocese of Los Angeles) |
| 1976.06.28 | Apostolic Exarchate of United States of America (Greek-Melkite Rite) was promoted as Diocese of Newton |
| 1976.10.13 | Diocese of Reno was renamed as Diocese of Reno–Las Vegas |
| 1976.10.18 | Diocese of Alexandria was renamed as Diocese of Alexandria–Shreveport |
| 1977 | Territorial Abbacy of Belmont–Mary Help of Christians was suppressed (to Diocese of Charlotte) |
| 1977.03.01 | Diocese of Biloxi was established (from the suppressed Diocese of Natchez–Jackson) |
| 1977.03.01 | Diocese of Jackson was established (from the suppressed Diocese of Natchez–Jackson) |
| 1977.03.01 | Diocese of Natchez–Jackson was suppressed (to establish Diocese of Biloxi and Diocese of Jackson) |
| 1977.03.02 | Diocese of Houma–Thibodaux was established (from Metropolitan Archdiocese of New Orleans) |
| 1977.03.11 | Metropolitan Archdiocese of Munhall (Ruthenian Rite) was renamed as Metropolitan Archdiocese of Pittsburgh |
| 1977.06.27 | Diocese of Saint Maron of Detroit (Maronite Rite) was renamed as Diocese of Saint Maron of Brooklyn |
| 1978.07.14 | Diocese of San Bernardino was established (from Diocese of San Diego) |
| 1980.01.29 | Diocese of Lake Charles was established (from Diocese of Lafayette in Louisiana) |
| 1980.02.14 | Diocese of Great Falls was renamed as Diocese of Great Falls–Billings |
| 1980.07.29 | Diocese of Mobile was promoted as Metropolitan Archdiocese of Mobile |
| 1981.01.27 | Diocese of San Jose was established (from Metropolitan Archdiocese of San Francisco) |
| 1981.07.03 | Apostolic Exarchate of United States of America and Canada (Armenian Rite) was established |
| 1981.11.19 | Diocese of Metuchen was established (from Diocese of Trenton) |
| 1981.12.03 | Diocese of Van Nuys (Ruthenian Rite) was established (from Diocese of Parma) |
| 1982.01.11 | Apostolic Exarchate of United States of America (Chaldean Rite) was established |
| 1982.01.11 | Apostolic Exarchate of United States of America (Romanian Rite) was established |
| 1982.04.13 | Diocese of Victoria was established (from Diocese of Galveston–Houston, Metropolitan Archdiocese of San Antonio and Diocese of Corpus Christi) |
| 1982.08.17 | Diocese of Las Cruces was established (from Metropolitan Archdiocese of Santa Fe and Diocese of El Paso) |
| 1983.03.25 | Diocese of Lubbock was established (from Diocese of Amarillo and Diocese of San Angelo) |
| 1983.11.10 | Diocese of Colorado Springs was established (from Metropolitan Archdiocese of Denver and Diocese of Pueblo) |
| 1983.12.05 | Diocese of Saint Josaphat in Parma (Ukrainian Rite) was established (from Metropolitan Archdiocese of Philadelphia) |
| 1984.06.16 | Diocese of Palm Beach was established (from Metropolitan Archdiocese of Miami and Diocese of Orlando) |
| 1984.06.16 | Diocese of Venice was established (from Metropolitan Archdiocese of Miami, Diocese of Orlando and Diocese of Saint Petersburg) |
| 1985.08.03 | Apostolic Exarchate of United States of America (Chaldean Rite) was promoted as Diocese of Saint Thomas the Apostle of Detroit |
| 1986.06.16 | Diocese of Alexandria–Shreveport was renamed as Diocese of Alexandria (lost territory to establish Diocese of Shreveport) |
| 1986.06.16 | Diocese of Shreveport was established (from Diocese of Alexandria–Shreveport) |
| 1986.07.21 | Military Vicariate of United States of America was promoted as Military Ordinariate of Archdiocese for the Military Services of the United States |
| 1986.12.12 | Diocese of Tyler was established (from Diocese of Galveston–Houston, Diocese of Beaumont and Diocese of Dallas) |
| 1987.03.26 | Apostolic Exarchate of United States of America (Romanian Rite) was promoted as Diocese of Saint George’s in Canton |
| 1988.01.14 | Diocese of Lexington was established (from Metropolitan Archdiocese of Louisville and Diocese of Covington) |
| 1988.05.27 | Diocese of Knoxville was established (from Diocese of Nashville) |
| 1994.02.19 | Diocese of Our Lady of Lebanon of Los Angeles (Maronite Rite) was established (from Diocese of Saint Maron of Brooklyn) |
| 1995 | Titular Episcopal See of Alton was restored |
| 1995 | Titular Episcopal See of Bardstown was restored |
| 1995 | Titular Episcopal See of Concordia was restored |
| 1995 | Titular Episcopal See of Grass Valley was restored |
| 1995 | Titular Episcopal See of Jamestown was restored |
| 1995 | Titular Episcopal See of Kearney was restored |
| 1995 | Titular Episcopal See of Lead was restored |
| 1995 | Titular Episcopal See of Leavenworth was restored |
| 1995 | Titular Episcopal See of Natchitoches was restored |
| 1995 | Titular Episcopal See of Nesqually was restored |
| 1995 | Titular Episcopal See of Quincy was restored |
| 1995 | Titular Episcopal See of Sault Sainte Marie was restored |
| 1995 | Titular Episcopal See of Vincennes was restored |
| 1995.03.21 | Diocese of Las Vegas was established (from Diocese of Reno–Las Vegas) |
| 1995.03.21 | Diocese of Reno–Las Vegas was renamed as Diocese of Reno (lost territory to establish Diocese of Las Vegas) |
| 1995.11.06 | Diocese of Our Lady of Deliverance of Newark (Syrian Rite) was established |
| 1996 | Titular Metropolitan See of Oregon City was restored |
| 1996 | Titular Episcopal See of Sault Sainte Marie was renamed as Titular Episcopal See of Sault Sainte Marie in Michigan |
| 2000.07.03 | Diocese of Laredo was established (from Metropolitan Archdiocese of San Antonio and Diocese of Corpus Christi) |
| 2001.03.13 | Diocese of Saint Thomas the Apostle of Chicago (Syro-Malabar Rite) was established |
| 2002.05.21 | Diocese of Saint Peter the Apostle of San Diego (Chaldean Rite) was established (from Diocese of Saint Thomas the Apostle of Detroit) |
| 2004.12.29 | Diocese of Galveston–Houston was promoted as Metropolitan Archdiocese of Galveston–Houston |
| 2005.09.12 | Apostolic Exarchate of United States of America and Canada (Armenian Rite) was promoted as Diocese of Our Lady of Nareg in New York |
| 2010.02.10 | Diocese of Van Nuys (Ruthenian Rite) was renamed as Diocese of Holy Protection of Mary of Phoenix |
| 2010.07.14 | Apostolic Exarchate of United States of America (Syro-Malankar Rite) was established |
| 2012.01.01 | Personal Ordinariate of The Chair of Saint Peter (Anglican Rite) was established |
