https://www.law.cornell.edu/uscode/text/50/98

The United States Code is meant to be an organized, logical compilation of the laws passed by Congress. At its top level, it divides the world of legislation into fifty topically-organized Titles, and each Title is further subdivided into any number of logical subtopics. In theory, any law -- or individual provisions within any law -- passed by Congress should be classifiable into one or more slots in the framework of the Code. On the other hand, legislation often contains bundles of topically unrelated provisions that collectively respond to a particular public need or problem. A farm bill, for instance, might contain provisions that affect the tax status of farmers, their management of land or treatment of the environment, a system of price limits or supports, and so on. Each of these individual provisions would, logically, belong in a different place in the Code. (Of course, this isn't always the case; some legislation deals with a fa