Yavapai County was named after the Yavapais Indian Tribe. Their name means the "people of the sun." Yavapai was the first county created by the Territorial Legislature. It was called the "Mother of Counties" from which Apache, Coconino, Gila, Maricopa, and Navajo counties where all formed. The County was originally 65,000 square miles and was formed in September of 1864.

The county area was so tremendous that subsequently it was divided to form six complete counties and parts of others. As originally established, Yavapai County reached from the New Mexico line on the east to the middle of the Gila River on the south and north to the Utah boundary. Its western boundary has not changed since its creation. Spanish explorers also traveled through Yavapai County . Antonio de Espejo visited the Jerome area in 1581, Juan de Onate explored the area in 1604 and Friar Francis Garces visited in 1776.

Today Yavapai County reflects the history of the old west and the future of the new. Remnants of U.S. Cavalry forts, Indian dwellings, gold rush boomtowns, abandoned mines, Spanish Land Grant ranches, homesteads and vast tracts of uninhabited public lands exist side by side with modern housing developments, industry and business here in the mountain heart of Arizona.