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.
According to the U.S. Census Bureau, the county has a total area of 4,203 square miles (10,890 km), of which 3,918 square miles (10,150 km) is land and 286 square miles (740 km) (6.8%) is water.
There are 2.25 persons per square mile, making this one of the most sparsely populated counties in California. It is also (almost) the only rectangular county in California, there is a slight deviation around the Tule Lake National Wildlife Refuge.
The county is very diverse geographically. The northwestern edge of the county is dominated by the Medicine Lake Highlands, the largest shield volcano on the U.S. West Coast. The Lava Beds National Monument lies partly within the northwest corner of the County. Also along the western edge of the county is the massive Glass Mountain lava flow. The southwestern corner of the county is a unique ecosystem of isolated hardwoods (oaks) and volcanic mountains with intermountain river valleys.
The northern half of the county is the Modoc Plateau, a 1-mile (1.6 km) high expanse of lava flows, cinder cones, juniper flats, pine forests, and seasonal lakes, plus the alkaline Goose Lake. Nearly 1 million acres (4,000 km²) of the Modoc National Forest lie on the plateau between the Medicine Lake Highlands in the west and the Warner Mountains in the east. The plateau supports large herds of mule deer (Odocoileus hemionus), Rocky Mountain Elk (Cervus canadensis), and pronghorn (Antilocapra americana). There are also several herds of wild horses on the plateau. The Clear Lake National Wildlife Refuge and Long Bell State Game Refuge are located on the plateau as well. The Lost River watershed, which later drains into the Klamath River basin, drains the north part of the plateau, while southern watersheds either collect in basin reservoirs or flow into the large Big Sage Reservoir, which sits in the center of the county, which later flows into the Pit River.
Below the rim of the Plateau is Big Valley in the extreme southwest corner of the county, and the large Warm Springs Valley that forms the bottom of the Pit River watershed that runs through the county. The north fork and south fork of the Pit River come together just south of Alturas. The River collects hundreds of other small creeks as it flows south towards Lake Shasta, where it joins the Sacramento River and drains into the San Francisco Bay.
The eastern edge of the county is dominated by the Warner Mountains. The Pit River originates in this mountain range. Hundreds of alpine lakes dot the range, all of which are fed by snow-melt and natural springs. East of the Warner Range is Surprise Valley and the western edge of the Great Basin.
Hot Springs and lava caves are common to Modoc County. There are some geothermal energy resources available in the county, though their viability is highly variable.
A great diversity of plants are found in Modoc County, since this is situated within the biodiverse California Floristic Province. Numerous native trees are found in the county including Garry Oak and Washoe Pine trees. Jeffrey Pine and Ponderosa Pine are also found in large numbers.
As of the census of 2000, there were 9,449 people, 3,784 households, and 2,550 families residing in the county. The population density was 2 people per square mile (1/km²). There were 4,807 housing units at an average density of 1 per square mile (0/km²). The racial makeup of the county was 85.9% White, 0.7% Black or African American, 4.2% American Indian, 0.6% Asian, 0.1% Pacific Islander, 5.7% from other races, and 2.8% from two or more races. 11.5% of the population were Hispanic or Latino of any race.
The largest ethnicity/ancestry groups in Modoc county include: 15% English, 14% Irish and 13% German of whom 90.4% spoke English and 8.8% Spanish as their first language.
There were 3,784 households out of which 29.1% had children under the age of 18 living with them, 54.6% were married couples living together, 8.8% had a female householder with no husband present, and 32.6% were non-families. 28.1% of all households were made up of individuals and 12.7% had someone living alone who was 65 years of age or older. The average household size was 2.39 and the average family size was 2.91.
In the county, the population was spread out with 25.6% under the age of 18, 5.7% from 18 to 24, 23.3% from 25 to 44, 27.7% from 45 to 64, and 17.6% who were 65 years of age or older. The median age was 42 years. For every 100 females, there were 102.4 males. For every 100 females age 18 and over, there were 98.7 males.
The median income for a household in the county was $27,522, and the median income for a family was $35,978. Males had a median income of $30,538 versus $23,438 for females. The per capita income for the county was $17,285. About 16.4% of families and 21.5% of the population were below the poverty line, including 29.7% of those under age 18 and 8.6% of those age 65 or over.
Modoc County has the lowest median household income of any county in California.
In 2005, the median home price reached $100,000 for the first time ever, over a 40% increase since 2000. Much of this can be traced to an influx of residents from other parts of the state, who find the housing bargains attractive. Some of these are retirees who have sold their houses for large profits in other parts of the state, using the proceeds to live on, while others are people who are able to telecommute. This sudden rise in housing prices become unaffordable for locals, who find themselves unable to purchase homes given their limited incomes.
The 2010 United States Census reported that Modoc County had a population of 9,686. The racial makeup of Modoc County was 8,084 (83.5%) White, 82 (0.8%) African American, 370 (3.8%) Native American, 78 (0.8%) Asian, 21 (0.2%) Pacific Islander, 680 (7.0%) from other races, and 371 (3.8%) from two or more races. Hispanic or Latino of any race were 1,342 persons (13.9%).