Some useful encyclopedias include:
Congress and the Nation provides less detailed analyses for major pieces of legislation than the coverage found in Congressional Quarterly Almanac.
Congressional Quarterly Almanac provides detailed analyses for most major pieces of legislation considered during a Congressional session.
Earlier volumes may be available in other local libraries, such as the Orlando Public Library (1951+). The earliest volumes for 1945-1950 are available at University of Florida (Gainesville) and University of South Florida (Tampa).
The narrative descriptions often track bills through the process, including discussion of the hurdles and compromises in committees. Sometimes these accounts focus on bills that failed to become law, but which received a lot of attention. For example, the 2002 volume devotes the entire five page Social Policy chapter to two issues: welfare reform and charitable choice. Congress failed to reach agreement on either issue. If these bills were reintroduced in subsequent sessions of Congress, then this analysis from 2002 might be useful for compiling part of the legislative history for those subsequent laws.
NOTE: Not every law is discussed, but search carefully before assuming that a particular law isn't covered; use the table of contents and the index to determine likely sections and then skim through those sections because the indexing is not comprehensive. Also check the volumes for earlier years and the following year.
If there is no coverage of a particular bill in the annual volume, there might be information available in CQ Weekly (step 8).