Map - Modoc County, California (Modoc County)

Modoc County is a county in the far northeast corner of the U.S. state of California. Its population is 8,700 as of the 2020 census, down from 9,686 from the 2010 census. This makes it California's third-least populous county. The county seat and only incorporated city is Alturas. Previous county seats include Lake City and Centerville. The county borders Nevada and Oregon.

Much of Modoc County is federal land. Several federal agencies, including the United States Forest Service, Bureau of Land Management, National Park Service, Bureau of Indian Affairs, and the United States Fish and Wildlife Service, have employees assigned to the area, and their operations are a significant part of its economy and services.

The county's official slogans include "The last best place" and "Where the West still lives".

Prior to the arrival of Europeans in the region, varying cultures of Native Americans inhabited the county for thousands of years. At the time of European encounter, the Modoc people lived in what is now northern California, near Lost River and Tule Lake. The county was named after them. The Achomawi (or Pit River Indians, for which the Pit River is named), and the Paiute also lived in the area. To the north were the Klamath in present-day Oregon.

The first European explorers to visit Modoc County were the American John C. Frémont and his traveling party (including Kit Carson) in 1846, who had departed from Sutter's Fort near the confluence of the American and Sacramento Rivers (where Sacramento stands today).

The northern boundary of California, and eventually Modoc County, had been established as the 42nd parallel since the time of Mexican possession. In the absence of a reliable survey of the 120th meridian, the eastern boundary of northern California was a subject of contention before Modoc County formed. The Territory of Utah requested jurisdiction to the summit of the Sierra Nevada. At the time, the Warner Mountains were believed to be a part of the Sierra Nevada, so this would have included Surprise Valley, but California denied the request.

In 1856, the residents of Honey Lake Valley reckoned the 120th meridian to be west of their valley, placing them in Utah territory, and attempted to secede and form a territory they called Nataqua. Nataqua would have included Modoc County. In 1858, the Territory of Nevada, with its capital now in Carson City, seceded from Utah, and assumed jurisdiction to the summit of the Sierra Nevada until the 120th meridian was surveyed in 1863.

After Nevada was granted statehood in 1864, the region of current Modoc County was placed within jurisdiction of Shasta County, California, and Siskiyou County was, in turn, generated from Shasta County in 1852.

Increasing traffic on the emigrant trail, unprovoked militia raids on innocent Modoc, and a cycle of retaliatory raids increased a cycle of violence between settlers and the tribes in the area. In 1864, the Klamath, Modoc and Yahooskin band of the Shoshone signed a treaty ceding lands in both Oregon and California, and the tribes were colocated on the Klamath Reservation. Harassed by the Klamath, traditional competitors, a band of Modoc led by Captain Jack returned to California and the Tule Lake area.

The Modoc War or Lava Beds War of 1872-73 brought nationwide attention to the Modoc. From strong defensive positions in the lava tubes, 52 Modoc warriors held off hundreds of US Army forces, who called in artillery to help. Peace talks in 1873 stalled when the Modoc wanted their own reservation in California. Warriors urged killing the peace commissioners, thinking the Americans would then leave, and Captain Jack and others shot and killed General Edward Canby and Rev. Eleazer Thomas, as well as wounding others. More Army troops were called in to lay siege to Captain Jack's Stronghold. Dissension arose, and some Modoc surrendered. Finally, most were captured, and those responsible for the assassinations were tried and executed. More than 150 Modoc were transported to Indian Territory as prisoners of war. The area has since been designated the Lava Beds National Monument.