Big Horn County was created by the legislature of Wyoming Territory in March 1890, and was organized in 1897; its area was annexed from Fremont, Johnson, and Sheridan counties. Big Horn County was named for the Big Horn Mountains which form its eastern boundary. Originally, the county included the entire Big Horn Basin, but in 1909 Park County was created from a portion of Big Horn County, and in 1911 Hot Springs and Washakie counties were created from portions of Big Horn, leaving the county with its present borders.
Geography
According to the US Census Bureau, the county has a total area of, of which is land and is water.
Big Horn County in Wyoming and Montana are one of ten pairs of counties and parishes in the United States with the same name to border each other across state lines. The others are Sabine, Union, Bristol, Kent, Escambia, Pike, Teton, Park, and San Juan.
As of the 2000 United States Census, there were 11,461 people, 4,312 households, and 3,087 families in the county. The population density was 4 people per square mile. There were 5,105 housing units at an average density of 2 per square mile. The racial makeup of the county was 94.03% White, 0.11% Black or African American, 0.75% Native American, 0.21% Asian, 0.07% Pacific Islander, 3.37% from other races, and 1.46% from two or more races. 6.17% of the population were Hispanic or Latino of any race. 23.0% were of German, 21.4% English, 8.1% American and 8.0% Irish ancestry. There were 4,312 households out of which 32.50% had children under the age of 18 living with them, 61.00% were married couplesliving together, 6.80% had a female householder with no husband present, and 28.40% were non-families. 25.00% of all households were made up of individuals and 11.90% had someone living alone who was 65 years of age or older. The average household size was 2.60 and the average family size was 3.13. The county population contained 28.70% under the age of 18, 7.30% from 18 to 24, 22.60% from 25 to 44, 24.60% from 45 to 64, and 16.80% who were 65 years of age or older. The median age was 39 years. For every 100 females there were 100.20 males. For every 100 females age 18 and over, there were 97.10 males. The median income for a household in the county was $32,682, and the median income for a family was $38,237. Males had a median income of $30,843 versus $19,489 for females. The per capita income for the county was $15,086. About 10.20% of families and 14.10% of the population were below the poverty line, including 19.20% of those under age 18 and 10.00% of those age 65 or over.
2010 census
As of the 2010 United States Census, there were 11,668 people, 4,561 households, and 3,179 families in the county. The population density was. There were 5,379 housing units at an average density of. The racial makeup of the county was 94.4% white, 0.9% American Indian, 0.3% Asian, 0.2% black or African American, 3.0% from other races, and 1.2% from two or more races. Those of Hispanic or Latino origin made up 8.4% of the population. In terms of ancestry, 30.0% were German, 22.3% were English, 10.4% were Irish, 7.6% were Scottish, and 5.7% were American. Of the 4,561 households, 31.0% had children under the age of 18 living with them, 58.2% were married couples living together, 7.6% had a female householder with no husband present, 30.3% were non-families, and 26.2% of all households were made up of individuals. The average household size was 2.52 and the average family size was 3.05. The median age was 41.8 years. The median income for a household in the county was $48,270 and the median income for a family was $57,705. Males had a median income of $40,762 versus $31,440 for females. The per capita income for the county was $24,486. About 5.7% of families and 8.9% of the population were below the poverty line, including 11.2% of those under age 18 and 7.1% of those age 65 or over.
Government and infrastructure
The Wyoming Department of Health Wyoming Retirement Center, a nursing home, is located in Basin. The facility was operated by the Wyoming Board of Charities and Reform until that agency was dissolved as a result of a state constitutional amendment passed in November 1990. Big Horn County voters have been reliably Republican for decades. They have selected the Republican Party candidate in every national election except one since 1936.
Education
Big Horn County has 4 public school districts, Big Horn County School Districts 1-4:
