San Juan County, New Mexico (Extinct)
The original San Juan was a county of New Mexico from 1861 to 1862. Later a different county was created with the same name, which exists to the present. Look for records of San Juan county (extinct) in the Taos county offices.
12 Jan 1861 - SAN JUAN county (original, extinct) created by New Mexico Territory from TAOS county. It stretched west to the California border, including land in present day Arizona, Nevada. (N.M. Terr. Laws 1860-1861, 10th assy. /p. 16)
18 Jan 1862 - SAN JUAN county (original, extinct) lost all territory to TAOS county when the law creating SAN JUAN was repealed. SAN JUAN was eliminated. (N.M. Terr. Laws 1861-1862, 11th assy. /p. 16)