From an LII Blog Post:
The LII’s U.S. Code collection received a major upgrade last week with the addition of USC-prelim. Thanks to our friends at the U.S. House of Representatives Office of the Law Revision Counsel (OLRC), the LII now includes all newly codified legislation for each title on a separate tab within each page of the LII U.S. Code Collection, right alongside the most recent official version.
The official version of the U.S. Code as released by the U.S. Government Printing Office can be as many as 15-18 months out of sync with current legislation. The OLRC has long realized that professional users of the code would benefit from access to the most current information available, and now the OLRC has agreed to release this information in bulk, as soon as practical, so we can offer it without fee to LII users. USC-prelim has been available on the OLRC government site for some time, but now you can find it in navigable form at the LII.
Bear in mind that while USC-prelim is far more current than the official release, these updates may be subject to further revision. Users should verify the text against the printed slip laws available from the Government Printing Office, the laws as shown on THOMAS (a legislative service of the Library of Congress), and the final version of the Code when it becomes available.