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.
(Enacted by Stats. 1935, Ch. 29.)