If you have not yet registered with USSA attached is the information for doing so. You can not race in Jackson Dec. 16-17, Casper Jan 20-21, or Laramie Feb 10-11 without USSA membership. They are all USSA affiliated races.
Here is the link: http://my.ussa.org/membership/start
Here is more information on registering: ussainfoforlanderskiteammembers2016