The United States Census is mandated by the U.S. Constitution. The first census taken was in 1790 and the census is retaken every 10 years. The information collected varied with each census depending on the needs of the Federal Government. From 1790 to 1840, only heads of households were listed by name. Beginning with the 1850 census, all members of a household were listed.
The 1790 to 1940 censuses are currently available to the public. The 1950 United States Census is scheduled to be released on April 1, 2022. Please see the National Archives site for more information about availability of the 1950 census records.
All of the National Archives microfilm publications relating to Pennsylvania, including the federal population census 1790-1930 (except for 1890 which was destroyed by fire in 1921) are in the collection. The 1940 census is only available online. Except for 1870 there is a name index for each of the Pennsylvania population census schedules. Book indexes list the heads of families from 1790 through 1860. For 1870, only portions of the Pennsylvania census have been indexed. The 1880 Soundex Index includes only households with children aged ten years and younger but the 1900 Soundex Index and the 1910 Miracode Index include all heads of families.
Search the State Library catalog.
Search the 1940 Census online.
Information found in census records can be used to locate other records about an individual. The National Archives has several pages listing the genealogical clues that can be found in records for each census.
Census Records for Latin America and the Hispanic United States by 
Your Guide to the Federal Census by 
State Census Records by Soundex is a coded index based on the way a surname (last name) sounds instead of the way it is spelled. Using the Soundex system makes it easier to locate a name that has been spelled in a variety of ways.
The Rootsweb Soundex converter tool will convert a surname to its corresponding Soundex code.
During the 1850, 1860, 1870 and 1880 censuses, information was collected for special nonpopulation census schedules in addition to the population schedules. Agricultural, Industry and Manufacturing, Mortality, Slave and Delinquent, Defective and Dependent Classes schedules were completed during this period.
The federal mortality schedules for Pennsylvania, 1850-1880 and book indexes for 1850, 1860 and 1870 are in the State Library collection. The mortality schedules list persons who died within one year preceding June 1 of 1850, 1860, 1870 or 1880. Cause of death is frequently recorded.
Census records are available through several electronic databases. Family Search is a free database that includes census records. Ancestry Library Edition is available for onsite use at the State Library. Current Commonwealth of Pennsylvania employees can access HeritageQuest to search census records remotely with their State Library of PA library card by visiting the State Library's Electronic Resources Guide.
Original Caption: Fairlington, VA. This census enumerator is getting data from a Virginia housewife for the 1950 Census. Photo by State Department-Mottar.
National Archives Identifier: 207899869
Local Identifier: 306-PS-50-3034
Creator(s): U.S. Information Agency. (8/24/1982 - 10/1/1999) (Most Recent)
U.S. Information Agency. Press and Publications Service. Visual Services Branch. Photo Library. (1953 - 4/1/1978) (Predecessor)
International Communication Agency. Press and Publications Service. Publications Division. (4/1/1978 - 8/24/1982) (Predecessor)
From: Series: Master File Photographs of U.S. and Foreign Personalities, World Events, and American Economic, Social, and Cultural Life, ca. 1953 - ca. 1994
Record Group 306: Records of the U.S. Information Agency, 1900 - 2003
Original Caption: Here is a condensed version of the 1950 Census tabulation picture. In the foreground is a punch card machine. Holes are punched in the card according to a prearranged code, transferring the facts from the questionnaire into statistics. The man operating the machine labeled “140” is running a sorter. This machine sorts cards into any desired classification. The other two machines are tabulators which add up the final results.
National Archives Identifier: 207527227
Local Identifier: 29-CM-C-15
Creator(s): Department of Commerce. Bureau of the Census. Public Information Office. 1890 ?-4/1983 (Most Recent)
From: Series: Census Machines, 1890 - 1950
Record Group 29: Records of the Bureau of the Census, 1790 - 2007
Original Caption: The latest invention in the field of electronics being put to use in tabulating the returns of the 1950 Census. The Electronic Statistical Machine combines in one operation the work of sorting (right rear) and the work of counting (left rear).
National Archives Identifier: 207525023
Local Identifier: 29-CM-E-14
Creator(s): Department of Commerce. Bureau of the Census. Public Information Office. 1890 ?-4/1983 (Most Recent)
From: Series: Census Machines, 1890 - 1950
Record Group 29: Records of the Bureau of the Census, 1790 - 2007
Hand punching machine, Census. , None. [Between 1909 and 1940] [Photograph] Retrieved from the Library of Congress, https://www.loc.gov/item/2016823354/.
Original Caption: "WPA workers engaged in indexing 1920 U.S. Census records. Picture taken at the project, 63 Vesey Street, New York City."
National Archives Identifier: 175739355
Local Identifier: 69-N-39-13590-D
Creator(s): Federal Works Agency. Work Projects Administration. Division of Information. 7/1/1939-1943 (Most Recent)
From: Series: WPA Information Division Photographic Index, ca. 1936 - ca. 1942
Record Group 69: Records of the Work Projects Administration, 1922 - 1944
National Archives Identifier: 6200721
Local Identifier: 29-C-1B-20
Creator(s): Department of Commerce. Bureau of the Census. Administrative Service Division. Library and Information Services Branch. ca. 6/17/1941- ? (Most Recent)
From: Series: Photographs Documenting the Sixteenth Decennial Census, 1940 - 1941
Record Group 29: Records of the Bureau of the Census, 1790 - 2007
