Roman Catholic Dioceses in the USA before 1900

Our diocesan collections generally contain correspondence of bishops and miscellaneous collected material. The following outline indicates how dioceses split and how new dioceses were created in the nineteenth century. This outline does not always represent all the complicated details of historical transitions. Some new dioceses covered territory previously assigned to two other dioceses; others existed as vicariates apostolic before they became dioceses. American history has its own complications. In the late eighteenth century, Baltimore was the only diocese in the United States, but other dioceses or archdioceses (Louisiana and the Floridas, Quebec, Mexican dioceses) had authority over territory later to become part of the United States. This list includes only dioceses founded before the 20th century.

> indicates a transfer of episcopal seat or change of name.

Baltimore 1789
---- Bardstown > Louisville 1808
---------- Cincinnati 1821
---------------- Detroit 1833
---------------------- Milwaukee 1843
---------------------------- La Crosse 1868
---------------------------- Green Bay 1868
---------------------- Sault St Marie > Marquette 1857
---------------------- Grand Rapids 1882
---------------- Cleveland 1847
---------------- Columbus 1868
---------- Vincennes > Indianapolis 1834
---------------- Chicago 1843
---------------------- Quincy > Alton > Springfield in Illinois 1853
---------------------------- Belleville 1887
---------------------- Peoria 1875
---------------- Fort Wayne > Fort Wayne / South Bend 1857
---------- Nashville 1837
---------- Covington 1853
---- Boston 1808
---------- Hartford 1843
---------------- Providence 1872
---------- Burlington 1853
---------- Portland 1853
---------------- Manchester 1884
---------- Springfield 1870
---- New York 1808
---------- Albany 1847
---------------- Ogdensburg 1872
---------------- Syracuse 1886
---------- Buffalo 1847
---------------- Rochester 1868
---------- Brooklyn 1853
---------- Newark 1853
---------------- Trenton 1881
---- Philadelphia 1808
---------- Pittsburgh 1843
---------------- Erie 1853
---------- Harrisburg 1868
---------- Scranton 1868
---- Richmond 1820
---------- Wheeling 1850
---------- Wilmington 1868
---- Charleston 1820
---------- Savannah 1850
---------------- St Augustine 1870

Louisiana and the Floridas > New Orleans 1793
---- St Louis 1826
---------- Dubuque 1837
---------------- St Paul 1850
---------------------- St Cloud 1889
---------------------- Winona 1889
---------------- Davenport 1881
---------- Little Rock 1843
---------- Vicariate Apostolic of the Indian Territory 1850
---------------- Omaha 1885
---------------------- Lincoln 1887
---------------------- Cheyenne 1887

---------- St Joseph > Kansas City / St Joseph 1868
---------- Leavenworth > Kansas City in Kansas 1877
---------------- Concordia > Salina 1887
---------------- Wichita 1887
---------- Kansas City > Kansas City / St Joseph 1880
---- Mobile 1829
---- Natchez 1837
---- Natchitoches > Alexandria 1853

(Mexico)
---- Both Californias > Monterey / Los Angeles 1840
---------- San Francisco 1853
---------------- Grass Valley > Sacramento 1868
---- Galveston 1847
---------- San Antonio 1874
---------- Dallas 1890
---- Santa Fe 1853
---------- Denver 1887
---------- Tucson 1897
---- Salt Lake City 1891

Oregon City > Portland in Oregon 1846
---- Nesqually > Seattle 1850
---- Vicariate Apostolic of Idaho 1868
---------- Helena 1884
---------- Boise 1893