Arizona County Creation Dates and Parent Counties

United States Arizona  County Creation Dates

Arizona Territory was created on 24 February 1863 from the west half of New Mexico Territory. All previous New Mexico counties were discontinued, but it was not until 10 November 1864, when the first four Arizona counties were created. Pah-Ute county is the only county discontinued, in 1871. All the other created counties still continue. The last county created was La Paz on 27 April 1983.

In the present day there are a total of 15 counties; 8 of them named for Native American Tribes, 2 of them for People, 2 of them for Mountains, 2 of them for Rivers, and 1 of them for a Town.


 * An animated map of Arizona county changes is found at Pima County History (scroll down)
 * Arizona Atlas of Historical County Boundaries contains detailed information of historical county boundary changes.

The information listed below is useful in identifying which county your ancestor lived in at what time. Once you have that information, you can contact that county's offices for records of your ancestor. If you don't find records in the identified county, look in nearby counties. Some changes have been made to the boundaries of the counties.