Section 25 Of General Provisions From California Streets And Highways Code

. As used in this code, "county highway" means any highway which is:
  (a) Laid out or constructed as such by the county.
  (b) Laid out or constructed by others and dedicated or abandoned to or acquired by the county.
  (c) Made a county highway in any action for the partition of real property.
  (d) Made a county highway pursuant to law.