Location
Cimarron County is the only county in the United States that borders on four states: Colorado, Kansas, New Mexico, and Texas. As a result, Cimarron County is the only county in the United States to border at least five counties from five different states (one from each of the four aforementioned states, plus one in Oklahoma and a second county in Texas). According to the United States Census Bureau, the county has a total area of 1,841 square miles (4,768 km2), of which 1,835 square miles (4,753 km2) is land and 6 square miles (16 km2) (0.33%) is water.

It also has Oklahoma's highest point at 4,973 feet (1,516 m) above sea level on the Black Mesa. A location 300 yards east of Rt. 287/385 1.75 miles south of the Cimarron River is the only place in the US less than 27 miles from five different states: 26.99 miles from Kansas, New Mexico, and Texas and seven miles from Colorado.

Population Density
As of the census of 2000, there were 3,148 people, 1,257 households, and 868 families residing in the county. The population density was 2 people per square mile (1/km²). There were 1,583 housing units at an average density of 1 per square mile (0/km²). The racial makeup of the county was 85.77% White, 0.57% Black or African American, 1.02% Native American, 0.16% Asian, 9.94% from other races, and 2.54% from two or more races. 15.41% of the population were Hispanic or Latino of any race.

There were 1,257 households out of which 31.30% had children under the age of 18 living with them, 60.40% were married couples living together, 6.00% had a female householder with no husband present, and 30.90% were non-families. 29.30% of all households were made up of individuals and 15.50% had someone living alone who was 65 years of age or older. The average household size was 2.47 and the average family size was 3.07.

In the county, the population was spread out with 27.60% under the age of 18, 6.40% from 18 to 24, 23.40% from 25 to 44, 24.00% from 45 to 64, and 18.60% who were 65 years of age or older. The median age was 39 years. For every 100 females there were 97.40 males. For every 100 females age 18 and over, there were 95.30 males.

Household Income
The median income for a household in the county was $30,625, and the median income for a family was $36,250. Males had a median income of $24,327 versus $18,110 for females. The per capita income for the county was $15,744. About 13.90% of families and 17.60% of the population were below the poverty line, including 22.20% of those under age 18 and 10.10% of those age 65 or over.