The 1930 Census was begun on 2 April 1930, with the exception of Alaska, where the official start date was 1 October 1929.

Due to boundary modifications in Europe resulting from World War I, some individuals were uncertain about how to identify their national origin. Enumerators were instructed to spell out the name of the city, state, province, or region of respondents who declared that they or their parents had been born in Germany, Austria-Hungary, Bulgaria, Russia, or Turkey. Interpretation of the birthplace varied from one enumerator to another. For the 1930, distinction was made between the Irish Free State and Northern Ireland, and also between Canada-French and Canada-English.

There are no separate Indian population schedules in the 1930 census. Inhabitants of reservations were enumerated in the general population schedules but some minor differences in reporting were used: in place of country of birth for the father, the degree of Indian blood was listed and for the country of birth for the mother the tribe was listed.

Enumerators were instructed not to report servicemen in the family enumerations but to treat them as residents of their duty posts. The 1930 census includes schedules for overseas military and naval forces.

Enumeration district numbering was altered for 52 of the 56 states and territories enumerated. Within each state, each county was assigned a number based on the alphabetical order of the county. That number would then be followed by the specific enumeration numbers for that county: i.e., 1-1, 1-23, 5-2, 10-73. American Samoa, the Canal Zone, Guam, and the Virgin Islands did not use this system.

Find out more about the 1930 United States Federal Census (not a free trial).