Question: How can I locate old Federal statutes?

There are two subject indexes to the older federal statutes. Both sets contain a "Table of Repeals and Amendments to the Statutes at Large" and a popular name table. 

• Beaman & McNamara's Index Analysis of the Federal Statutes 1789-1873 (SMITH KF80 .B43 1987)
• McClenon & Gilbert's Index to the Federal Statutes 1874-1931 (SMITH KF80 .S36 1993)
  • Also contains a List of Statutory Definitions and a List of Treaties with Statutes at Large citations

Each volume of Statutes at Large has its own index, which is helpful if you know the approximate date that a particular law was passed. 

Superseded sets of compiled statutes will show what the text of a frequently amended law looked like in a particular year.

• See the Revised Statutes of the U.S. in the Retro collection.