Bills are designated H.R. if they originate in the House of Representatives and S. if they originate in the Senate, and are given a number, which is in the chronological order with which they are introduced during the two-year period of a congressional term. (See also Concurrent Resolution, Joint Resolution.) Public bills deal with general questions and become public laws if approved by Congress and signed by the president. Private bills deal with individual matters such as claims against the government, immigration and naturalization cases, and become private laws if approved and signed. Each printed version of a bill usually has some changes, allowing comparisons and illuminating choices made as the legislation developed. Varieties include: as introduced, as referred, enrolled,engrossed, and enacted bills. To track changes in legislation, GovTrack and Many Bills will help.
Historical Bills: (House 1799-1873) (Senate 1819-1873):
LoC American Memory web site
Bills issued between 1874 - 1932:
See a reference librarian
Bills issued between 1933 - 1989:
CIS Fiche Set (UES Law Library): 1933 – 1979
GPO fiche (UES law library): 1979 – 1989
Proquest Legislative Insight: 1929 - forward (in progress) for legislation that became law.
Bills issued after 1989:
Thomas (HTML and PDF): 1989 - date
U.S. GPO (PDF): 1993 – date
Lexis: 1989 - date
Westlaw: 1995 - date