If you are looking for the history of an enacted law, you will need the Public Law number. The US Code contains Public Law and Statutes at Large annotations.
v.1 (1789)- v.44 (1927)
Early US Statutes at Large; full-text from the University of Cincinnati
v.50 (1937)- most recent received:
In print or microform at McHenry library:
---Statutes at Large: v.50 (1937) - v.88 (1974)
---US Code Congressional and Administrative News: v.89 (1975) to most recent received
v.87 (1973) - current
THOMAS: full-text of the enrolled bills by Public Law number. See "Congressional Actions" for relevant dates, votes, and reports (linked when available)
v.101 (1987) - current (Requires UCSC or OCA access).
ProQuest Congressional: Full text of for 100th (1987) congress to current. Includes annotations to USC, Bills, Reports, Hearings, and Congressional Record.
v.109 (1995) - current
GovInfo: Public and Private Laws collection
Use the citations from the Public Laws or search by keyword and congress for House and Senate reports and Committee prints.
The debates of Congress and record of votes can be found in the Congressional Record which is published daily.
The Congressional Research Service provides Congress with nonpartisan research and analysis of a wide range of public policy issues. CRS reports are not immediately available to the public and they must be accessed indirectly through other sources. None of these sites offer a full collection of CRS reports. Also refer to this CRS Guide from the University of Colorado at Boulder.