It may be useful to compare various versions of a bill as it moves through the legislative process.
THOMAS, from the Library of Congress, has Bill Tracking Reports for Public Laws (from 1973)
LexisNexis Congressional Bill Tracking (from 1989)
GovTrack.us is a non-commercial, non-partisan, community & open source project. Based on THOMAS data, the House and Senate websites, and related sources, GovTrack allows users to set up monitors, customized email alerts and RSS feeds.
OpenCongress is supported by the Sunlight Foundation and draws heavily on the files available through the GovTrack project. The site also integrates blogs and online news sources.
News and Background Information
