Tom Blasingame, the oldest cowboy in the history of the American West, lived in Armstrong County and worked for seventy-three years in ranching, mostly on the JA Ranch.
Ranch historian Laura Vernon Hamner interviewed many "old-timers" in Armstrong County during the last decade of the 19th century and the first decade of the 20th century in preparation for her later writings on the Texas Panhandle.
As of the census of 2000, there were 2,148 people, 802 households, and 612 families residing in the county. The population density was 2 people per square mile (1/km²). There were 920 housing units at an average density of 1 per square mile (0/km²). The racial makeup of the county was 95.44% White, 0.28% Black or African American, 0.65% Native American, 2.79% from other races, and 0.84% from two or more races. 5.40% of the population were Hispanic or Latino of any race.
There were 802 households out of which 33.90% had children under the age of 18 living with them, 67.20% were married couples living together, 6.10% had a female householder with no husband present, and 23.60% were non-families. 21.40% of all households were made up of individuals and 12.00% had someone living alone who was 65 years of age or older. The average household size was 2.58 and the average family size was 2.99.
In the county, the population was spread out with 26.00% under the age of 18, 6.10% from 18 to 24, 24.80% from 25 to 44, 23.80% from 45 to 64, and 19.20% who were 65 years of age or older. The median age was 41 years. For every 100 females there were 93.20 males. For every 100 females age 18 and over, there were 90.30 males.
The median income for a household in the county was $38,194, and the median income for a family was $43,894. Males had a median income of $30,114 versus $21,786 for females. The per capita income for the county was $17,151. About 7.90% of families and 10.60% of the population were below the poverty line, including 15.80% of those under age 18 and 11.60% of those age 65 or over.