Section 318 Of Article 3. The State Highway Routes From California Streets And Highways Code >> Division 1. >> Chapter 2. >> Article 3.

. Route 18 is from:
  (a) Route 10 near San Bernardino to Route 210.
  (b) Route 210 near San Bernardino to Route 15 in Victorville via Big Bear Lake.
  (c) Route 15 near Victorville to Route 138 near Pearblossom.