United States New Mexico Santa Ana County
Santa Ana County was created as an original county of New Mexico Territory in 1852 from an old Mexican partido. In theory it extended west to the California border including parts of Arizona and later Nevada. Arizona Territory was carved out of the western part of New Mexico including part of this county on 29 December 1863. The remaining Santa Ana county in New Mexico was discontinued and absorbed by Bernalillo County in 1876.
The first county seat was Fort Defiance just west of the current Arizona-New Mexico border. For 1847 to 1863 it was part of Judicial District 1, and thereafter Judicial District 2.