Lassen County

Lassen County () is a county in the northeastern portion of the U.S. state of California. As of the 2010 census, the population was 34,895. The county seat and only incorporated city is Susanville. Lassen County comprises the Susanville, California, micropolitan statistical area. A former farming, mining and lumber area, its economy now depends on employment at one federal and two state prisons; the former in Herlong and the latter two in Susanville. In 2007, half the adults in Susanville worked in one of the facilities.
Lassen County was formed on April 1, 1864, from parts of Plumas and Shasta counties following the two-day conflict known as the Sagebrush War, also called the Roop County War, that started on February 15, 1863. Due to uncertainties over the California border, the area that is now Lassen County was part of the unofficial Nataqua Territory and Roop County, Nevada, during the late 1850s and early 1860s.

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