A current copy of the Tennessee Code Annotated (TCA) can be found in the Reserve Reading Room on the first floor. There are also copies on Secured Reserve and the fourth floor. Previous editions are on Secured Reserve and on the fourth floor. The TCA is available online.
The United States Code can be found on the first floor in the tall stacks. Prior versions are on the third floor. You can access the U.S. Code online through the FDSys database.
State codes are found on the fourth floor in alphabetical order. To find a state code online, search for "state name code" in your preferred search engine.