California Code
ARTICLE 3 - Settlement of Boundary Disputes
Section 23170.

23170. Every common boundary between counties which has been mutually recognized and used by the counties adjacent thereto for the purpose of the assessment and collection of taxes for a period of 25 years continuously prior to July 30, 1927, is confirmed, validated, and declared to be legally established.

(Added by Stats. 1947, Ch. 424.)