The IGS collection of census materials consists of:
Federal Censuses -IGS has microfilm of 1790 – 1870 census for all of the states whose census exists for those years. The 1880, 1900, 1910, 1920, and 1930 censuses are not complete, except for Iowa.
Printed indexes to most census records for the majority of states for the years 1790 through 1860, with some for 1870 as well. Indexes are also on microfiche.
The Soundex (a phonetic index on microfilm) for Iowa for 1880, 1900, and 1920 and scattered ones for other states.
Iowa Mortality Schedules for 1850, 1860, 1870, and 1880 taken at the time of the census, listing those who died in the year preceding the actual enumeration. (All four are on microfilm. The 1850 is also in print [977.7/GEN] and the 1880 is also in print, located with the census index books.
State census records for 1856, 1885, 1895, 1915, and 1925, which are not indexed state-wide. These contain many pieces of information not found in the Federal census records, such as the 1925 census which asked the names and birthplaces of the parents of everyone enumerated.
There are also several state census records listing only head-of household for various years from 1836-1854. Most are not indexed.
Nebraska and Kansas state census records for 1885.
Wisconsin state census records for 1855, 1875, and 1895.
1900 Census of Indian Territory Census – Cherokee, Chickasaw, Choctaw, Creek Nation; as well as other miscellaneous census for Olls, Sac & Fox in Tama, Iowa, for various years.