Mohave County, at the time of its creation by Arizona’s first Territorial Assembly in 1864, actually included portions of present day Nevada. In 1865, the northern portion of Mohave County was split off as Pah-Ute County. And in 1867, parts of both counties – including the present site of Las Vegas – were attached to Nevada, which had become a state in 1864. The much reduced Pah-Ute County was merged with Mohave County in 1871. Today, most of the historic sites of "Arizona’s Lost County" are covered by the waters of Lake Mead.

The area that is now Mohave County began to attract settlers shortly after it was brought into the United States by the Treaty of Guadalupe Hidalgo in 1848. The 1860s saw an influx of miners after gold was discovered, and Mormons who were sent south from Utah by their church.

Mohave County is geographically the second largest in the state. Most of it is classified as desert, but of its 13,470 square miles, 158 square miles are water. The county boasts 1,000 miles of shoreline and is a great water sports center. It also has the longest stretch of historic Route 66. The Colorado River and two man-made lakes, Lake Mohave and Lake Havasu, play an important role in the growth of Lake Havasu City and Bullhead City.

Kingman, the county seat, was not founded until the 1880s with the coming of the railroad. Before being moved to Kingman in 1887, the county seat had been located in the communities of Mohave City, Hardyville, Cerbat, and Mineral Park – none of which exist today. Although these communities did not survive, the forces that led to their establishment – mining, the Colorado River and the railroad – are still important to the county’s economy.

The U.S. Forest Service and Bureau of Land management own 61 percent of the land; Indian reservations, 6 percent; the state of Arizona, 7 percent; individual or corporate, 18 percent; and other public lands, 8 percent.