The Office of the Law Revision Counsel of the U.S. House of Representatives provides USCPrelim as a more up-to-date, unofficial text of the U.S. Code. They say:
This preliminary release may be subject to further revision before it is released again as a final version. As with other online versions of the Code, the U.S. Code Classification Tables should be consulted for the latest laws affecting the Code. Those using the USCPrelim should verify the text against the printed slip laws available from GPO (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.