United States Census Availability
Images of almost all federal censuses population schedules available at the National Archives are also now available online. Images of many federal non-population schedules are also available online. For links to the Internet version of federal censuses see the blue (population schedules) and orange (non-population schedules) tables on the Wiki census page for each state.
Only a few state, territorial, and colonial censuses are found on the Internet.
Many college and public libraries and archives also have microfilm copies of their state's federal census records.
National Archives Rentals
Censuses and other records that were microfilmed by the National Archives can be rented through them at: http://www.archives.gov/research/order/renting-microfilm.html
The National Archives and Records Administration has all surviving federal copies of United States federal census population schedules, and most non-population schedules. They do not grant access to originals except for special situations such as errors on microfilm copies.
Rarely, state or county draft copies of federal censuses can be found at state or county archives. States and counties are more likely to have non-population schedules than population schedules drafts.