Modoc County is a county in the far northeast corner of the U.S. state of California. As of the 2010 census, the population was 9,686. making it the third-least populous county in California. The county seat and only incorporated city is Alturas. Previous county seats include Lake City and Centerville; the latter is now a ghost town. The county borders Nevada and Oregon.
A large portion 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 the area's economy and services.
The county's official slogans include "The last best place" and "Where the West still lives".
• Lassen County, California - south
• Shasta County, California - southwest
• Siskiyou County, California - west
• Klamath County, Oregon - north
• Lake County, Oregon - north
• Washoe County, Nevada - east