Siskiyou County is in the Shasta Cascade region along with the Oregon border. Because of its outdoor recreation opportunities and Gold Rush era history, it is an important tourist destination within the state.
After the discovery of an important gold strike near today's Yreka, California, in 1851, prospectors flooded the area. This was described in detail by Joaquin Miller in his semi-autobiographical novel Life Amongst the Modocs.
In the mid 1880s, the construction of the Central Pacific Railroad along the Siskiyou Trail brought the first wave of tourism. Visitors were drawn by the county's many summer resorts, and to hunt or fish in the largely untouched region. The Southern Pacific railroad, the successor to the Central Pacific, called its rail line “The Road of A Thousand Wonders.”
In the early 1940s, Siskiyou County was home to the semi-serious State of Jefferson movement, which sought to create a new state from several counties of northern California and the adjoining counties of southern Oregon. The movement has seen a revival in recent years.
The origin of the word Siskiyou is not known. It may be Chinook word for a "bob-tailed horse", or as was argued before the State Senate in 1852, from the French Six Cailloux (six stones), a name given to a ford on the Umpqua River by and his Hudson's Bay Company trappers in 1832. Others claim the Six Cailloux name was appropriated by Stephen Meek, another Hudson's Bay Company trapper who discovered Scott Valley, for a crossing on the Klamath River near Hornbrook.
The County is home to the Black Bear Ranch, a commune started in 1968 with the slogan "Free Land for free people."
On September 4, 2013, the Siskiyou County Board of Supervisors voted 4 to 1 to secede from the State of California.
According to the U.S. Census Bureau, the county has a total area of 6,347 square miles (16,440 km2), of which 6,278 square miles (16,260 km2) is land and 69 square miles (180 km2) (1.1%) is water. It is the fifth-largest county by area in California.
Siskiyou County is geographically diverse. From towering Mount Shasta (elev. 14,179 ft/(4,322 m)) near the center of the county, to lakes and dense forests, as well as desert, chaparral, and memorable waterfalls, the county is home to world-famous trout-fishing rivers and streams, such as the Sacramento and McCloud rivers. The county is dotted as well with lakes and reservoirs, such as Castle Lake and Lake Siskiyou. Mount Shasta itself has a winter sports center. Pastoral Scott Valley in the western part of the county has many wide, tree-lined meadows, supporting large cattle ranches. The basins of northeastern Siskiyou County, including Butte Valley, Lower Klamath and Tule Lake basins, have some of the deepest and richest soils in the state, producing alfalfa, potatoes, horseradish, and brewing barley. Butte Valley nurseries are the leading source of premium strawberry plants in North America. Much of the county is densely forested with pine, fir, incense-cedar, oak, and madrone; Siskiyou County is also home to the rare Baker's Cypress Tree, Cupressus bakeri, which grows in only eleven scattered locations in the world, five of which are in Siskiyou County.
The county's natural resources are most often used these days for skiing, snowboarding, hiking, mountain biking, camping, and wilderness recreation, as historic logging practices have been largely discontinued due to Federal and State environmental regulations. The county's water is viewed as sufficiently pure and abundant that the county is a source of significant amounts of bottled water, distributed throughout the country. A large Crystal Geyser plant is at the base of Mt. Shasta, near Weed.
(STAGE) operates buses connecting the more populated areas of the county. Amtrak trains stop in Dunsmuir. Amtrak California motorcoaches operate from Sacramento and Medford, OR, with stops in Yreka, Weed, Mount Shasta, and Dunsmuir, for passengers connecting to and from Amtrak trains in Sacramento or Stockton.
On November 4, 2008, Siskiyou County voted 60.1% for Proposition 8 which amended the California Constitution to ban same-sex marriages. Dunsmuir and Mount Shasta voted against Prop 8.
On September 3, 2013, the Siskiyou County Board of Supervisors voted 4–1 in favor of secession from California to form a proposed state named Jefferson. A similar move was made in 1941, but was shelved due to the attack on Pearl Harbor.
The following table includes the number of incidents reported and the rate per 1,000 persons for each type of offense.
There were 18,556 households, out of which 27.6% had children under the age of 18 living with them, 51.7% were married couples living together, 10.1% had a female householder with no husband present, and 34.1% were non-families. 28.6% of all households were made up of individuals, and 12.8% had someone living alone who was 65 years of age or older. The average household size was 2.35 and the average family size was 2.87.
In the county, the population was spread out, with 24.0% under the age of 18, 6.7% from 18 to 24, 22.7% from 25 to 44, 28.4% from 45 to 64, and 18.1% who were 65 years of age or older. The median age was 43 years. For every 100 females there were 96.5 males. For every 100 females age 18 and over, there were 94.1 males.
The median income for a household in the county was $29,530, and the median income for a family was $36,890. Males had a median income of $31,936 versus $22,650 for females. The per capita income for the county was $17,570. About 14.0% of families and 18.6% of the population were below the poverty line, including 26.6% of those under age 18 and 7.3% of those age 65 or over.