Agriculture is the predominant source of income in this county, with vegetable, grass and flower seeds, garlic, mint and sugar beets cultivated on some 60,000 irrigated acres. Jefferson County also has vast acreages of rangelands and a healthy industrial base related to forest products. The Warm Springs Forest Products Industry, a multi-million dollar complex owned by the Confederated Tribes of the Warm Springs Reservation -- partially located in the northwestern corner of the county -- is the single biggest industry. With 300 days of sunshine and a low yearly rainfall, fishing, hunting, camping, boating, water-skiing and rock hunting are major tourist activities.
The major landowners in the county are the Forest Service, which owns 24% of the lands within the county boundaries, and the Warm Springs Reservation, which owns 21%.
According to the U.S. Census Bureau, the county has a total area of 4,639 km² (1,791 mi²). 4,612 km² (1,781 mi²) of it is land and 27 km² (10 mi²) of it is water. The total area is 0.58% water.
As of the census2 of 2000, there are 19,009 people, 6,727 households, and 5,166 families residing in the county. The population density is 4/km² (11/mi²). There are 8,319 housing units at an average density of 2/km² (5/mi²). The racial makeup of the county is 68.98% White, 0.26% Black or African American, 15.68% Native American, 0.30% Asian, 0.22% Pacific Islander, 11.32% from other races, and 3.23% from two or more races. 17.74% of the population are Hispanic or Latino of any race.
There are 6,727 households out of which 35.60% have children under the age of 18 living with them, 60.50% are married couples living together, 10.50% have a female householder with no husband present, and 23.20% are non-families. 18.60% of all households are made up of individuals and 6.90% have someone living alone who is 65 years of age or older. The average household size is 2.80 and the average family size is 3.16.
In the county, the population is spread out with 29.80% under the age of 18, 7.70% from 18 to 24, 26.90% from 25 to 44, 23.20% from 45 to 64, and 12.40% who are 65 years of age or older. The median age is 35 years. For every 100 females there are 101.90 males. For every 100 females age 18 and over, there are 100.80 males.
The median income for a household in the county is $35,853, and the median income for a family is $39,151. Males have a median income of $31,126 versus $22,086 for females. The per capita income for the county is $15,675. 14.60% of the population and 10.40% of families are below the poverty line. Out of the total people living in poverty, 22.20% are under the age of 18 and 5.90% are 65 or older.
Jefferson County was created on December 12, 1914 from a portion of Crook County. The county owes much of its agricultural prosperity to the railroad, which links Madras with the Columbia River, and was completed in 1911, and to the development of irrigation projects in the late 1930s. The railroad was completed despite constant feuds and battles between two lines working on opposite sides of the Deschutes River.
Madras was incorporated in 1911, and has been the county seat since the creation of the county.
Rapid development in adjacent Deschutes County, Oregon during the 1990s has farmers in Jefferson County concerned that they may be priced out of their own farmlands, which could be replaced by destenaion resorts, golf courses, and other amenities for recent arrivals.