Congress.gov
Congress.gov provides full text of multiple versions of bills. Additional information includes sponsors, related bills, and final bill status. You can search bills by keyword and number. 
Once you get your search results, you can narrow them down by various filters. For this class, the Subject - Policy Area filter will be very useful.
Provides multiple versions of bills. Search in: Legislative Histories, Bills & Laws section
Legislative Insight (Proquest)
Offers in-depth legislative histories of thousands of U.S. public laws. Includes various versions of the enacted bill. This is a work in progress--years and public laws covered are being updated continuously (currently runs through the 112th Congress - 2011).
FDsys (Government Printing Office), 1995-
Browse public laws by year and public law numerical order.
United States Statutes at Large
Annual volume(s) includes the text of public laws and other statutory documents (such as executive orders) issued during that year. Index and table of contents included.
Online
1789- (HeinOnline)
1951~ (FDsys)
