Popular name tables
Both the Texas statutes and the federal statutes have a Popular Name Table that allow a researcher to look up a statute by a commonly-known title. For instance, if you know you need to find the text of the Civil Rights Act of 1964, you can use the Popular Name Table in one of the sources for the United States Code (USC, USCA, or USCS) to find where that Act is located in the Code. In both the Texas and federal statutes, the Popular Names Table can be found at the end of the set of statutes or in separate index volumes.
Indexes
Both the federal and the Texas statutes have print subject-matter indexes to facilitate access to the statutes. If you are looking for a federal statute, it is probably best to use the indexes for one of the annotated sources (USCA or USCS), as opposed to the official version of the Code (USC). Generally, the commercial, annotated sources are more extensively indexed and also more up-to-date. The indexes will provide you with references to the relevant statutes.
In Texas, the General Index covers the entire set of Texas statutes--both the Revised Civil Statutes and the Codes.