Section 315 Of Article 3. The State Highway Routes From California Streets And Highways Code >> Division 1. >> Chapter 2. >> Article 3.

. Route 15 is from:
  (a) Route 5 in San Diego to Route 8.
  (b) Route 8 to the Nevada state line near Stateline, Nevada via the vicinity of Temecula, Corona, Ontario, Victorville, and Barstow.