Wanderlust World Wanderlust World A common point of confusion: La Paz is not a county in Arizona. It is a small unincorporated town located in Yuma County, in the state's far southwestern corner along the Colorado River.
The county seat of Yuma County is Yuma—not Parker, and not La Paz. Yuma is the largest city in the county and the administrative center.
Parker is the county seat of La Paz County—a different county, created in 1983 from the northern portion of Yuma County. La Paz County includes Parker, Quartzsite, and surrounding desert areas. The town of La Paz (the subject of this question) remained in Yuma County.
The name "La Paz" (Spanish for "peace") was given to the original 1860s gold-mining settlement on the Colorado River. When the new county was formed over a century later, it borrowed the historic name—creating the ongoing confusion.