thumb|Courthouse Rock in the Eagletail Mountains, northeastern La Paz County
thumb|Classic [[wulfenite specimen from the old Red Cloud Mine, western La Paz County]]
La Paz County () is the 15th county in the U.S. state of Arizona, located in the western part of the state. As of the 2020 census, its population was 16,557, making it the second-least populous county in Arizona. The county seat is Parker. The name of the county is the Spanish word for "the peace", and is taken from the early settlement (later ghost town) of La Paz along the Colorado River.
History
La Paz County was established in 1983 after voters approved separating the northern portion of Yuma County, making it the only county to be established after Arizona became a state in 1912, and currently the second youngest county in the United States (behind the consolidated city-county of Broomfield, Colorado, which was established in 2001). The county did not have a large enough tax base to begin supporting a separate county government immediately and had to rely on state money at first. As a result, the Arizona State Legislature changed Arizona laws to make splitting other existing counties much more difficult.
Under the revised Arizona laws, a county shall not be formed or divided by county initiative unless each proposed county would have all of the following characteristics: (1) at least three-fourths of one percent of the total state assessed valuation and at least the statewide per capita assessed valuation; (2) a population of at least three-fourths of one percent of the total state population according to the most recent United States decennial census; (3) at least one hundred square miles of privately owned land; (4) common boundaries with either (a) at least three other existing or proposed counties; or (b) at least two other existing or proposed counties and the state boundary. A county formation commission is required to be formed to evaluate the feasibility of the proposed county. A proposal to divide a county must be approved by a majority of the votes cast in each proposed new county. Yet in 2022 a group of Republican state legislators, motivated largely by partisan considerations, proposed dividing Maricopa County into four counties.
The Colorado River Indian Reservation is located in the western portion of the county. Part of the reservation extends westward into San Bernardino and Riverside counties in California.
Geography
According to the United States Census Bureau, the county has a total area of , of which is land and (0.3%) is water.
The area that now makes up La Paz County was formerly part of Yuma County.
Flora and fauna
thumb|upright|[[Hi Jolly monument near Quartzsite]]
La Paz County hosts a variety of flora and fauna. The endangered California Fan Palm Washingtonia filifera grows in a few spots in the county.
Adjacent counties
- Mohave County – north
- Yavapai County – northeast
- Maricopa County – east
- Yuma County – south
- Imperial County, California – southwest
- Riverside County, California – west
- San Bernardino County, California – northwest
National protected areas
- Bill Williams River National Wildlife Refuge (part)
- Cibola National Wildlife Refuge (part)
- Imperial National Wildlife Refuge (part)
- Kofa National Wildlife Refuge (part)