The Immigrant Ship Transcribers Guild is a volunteer effort to transcribed all ship's passenger lists for free use online. The U.S. Army Center of Military History should be contacted for WWI and later. The United States Bureau of Census , part of the Department of Commerce, is charged with organizing, collecting, and maintaining the decennial census required by the US Constitution. The genealogy section does not publish census records online but does provide general information. The USGenWeb Project has established the Census Project to make published census records available for free online.
Volunteers transcribe the detail data from the microfilms.
Some images of actual census returns will also be available. The SSA currently focuses on old-age insurance. This is simply a list of all people who were receiving benefits at the time of their death . It is not a complete list of everyone who ever had a Social Security account. There is a fee, check the SSA site for the latest costs.