All competitors in USSA sanctioned races are required to have a license. 

The approximate costs are as follows. (check USSA application form for 
current costs) 

USSA License plus Intermountain fee
          J5 Ages 10 and under	$80
          J4 Ages 11-12		$80
          J3 Ages 13-14		$175
          J2 Ages 15-16		$175
          J1 Ages 17-19		$175	

You can download the USSA membership form from the Applications and Forms page.  

You can get more information on the USSA Intermountain Division website.
http://www.ussa-imd.org