My fellow law librarians reminded me about the new United States Code (USC) Title 51 (which you will actually cite more like this: 51 USC xxx).
That USC Title 51 will (does!) sound strange to us old-timers. (Though not for the same reason it will confuse Area 51 devotees – and Title 51 is about Space Programs – ha ha ha.)
There isn’t yet a codification to find at the Cornell LI site or at the official FDSys United States Code site, but you can still look at the Session Law, P.L. 111-314 (enacted on December 18, 2010): Title 51, United States Code, National and Commercial Space Programs
U.S. Office of Law Revision Counsel brings us USC Title 51 (and main Positive Law website)
Related to this, is a reminder not to confuse U.S. session law (U.S. Statutes at Large) with its codified version (United States Code) or it’s commercial versions, U.S.C.S. (LexisNexis Matthew Bender) and U.S.C.A. (Thomson Reuters).