From Slip Law to United States Code: A Guide to Federal Statutes for Congressional Staff [May 2, 2018] [open pdf - 769KB]
"This report provides an overview of federal statutes in their various forms, as well as basic guidance for congressional staff interested in researching statutes. When a bill becomes a law, the newly enacted statute may amend or repeal earlier statutes or it may create a new or 'freestanding' law. Either way, these new statutes are first printed individually as 'slip laws' and numbered by order of passage as either public laws, or less frequently, private laws. Slip laws are later aggregated and published chronologically in volumes known as the United States Statutes at Large (Statutes at Large). Statutes of a general and permanent nature are then incorporated into the United States Code (U.S. Code), which arranges the statutes by subject matter into 54 titles and five appendices"
CRS Report for Congress, RL45190