|Area Total Sq Mi:||2814|
|Area Land Sq Mi:||2802|
|Area Water Sq Mi:||11|
According to the U.S. Census Bureau, the county has a total area of 2,814 square miles (7,287 km²), of which, 2,802 square miles (7,258 km²) of it is land and 11 square miles (29 km²) of it (0.40%) is water. The county attained its present boundaries on November 7, 1997, when the former Yellowstone National Park (part) county-equivalent was dissolved and apportioned between Gallatin County and Park County. Gallatin County received 99.155 square miles (256.81 km²) of land area and 0.119 square miles (0.309 km²) of water area, whereas Park County received 146.229 square miles (378.73 km²) of land area and 0.608 square miles (1.575 km²) of water area. The geographies transferred are known now as Census Tract 14 in Gallatin County, and as Census Tract 6 in Park County.
Park Counties in Montana and Wyoming are among the very few pairs of counties in the United States with the same name to border each other across state lines.
As of the censusWeb site: States Census Bureau] American FactFinder]. 2008-01-31. of 2000, there were 15,694 people, 6,828 households, and 4,219 families residing in the county. The population density was 6 people per square mile (2/km²). There were 8,247 housing units at an average density of 3 per square mile (1/km²). The racial makeup of the county was 96.65% White, 0.40% Black or African American, 0.92% Native American, 0.36% Asian, 0.03% Pacific Islander, 0.47% from other races, and 1.17% from two or more races. 1.84% of the population were Hispanic or Latino of any race. 23.5% were of German, 12.4% English, 9.5% Norwegian, 9.0% Irish and 7.9% American ancestry according to Census 2000.
There were 6,828 households out of which 28.10% had children under the age of 18 living with them, 51.00% were married couples living together, 7.30% had a female householder with no husband present, and 38.20% were non-families. 32.40% of all households were made up of individuals and 11.70% had someone living alone who was 65 years of age or older. The average household size was 2.27 and the average family size was 2.88.
In the county the population was spread out with 23.50% under the age of 18, 6.50% from 18 to 24, 27.90% from 25 to 44, 27.10% from 45 to 64, and 14.90% who were 65 years of age or older. The median age was 41 years. For every 100 females there were 97.40 males. For every 100 females age 18 and over, there were 96.10 males.
The median income for a household in the county was $31,739, and the median income for a family was $40,561. Males had a median income of $28,215 versus $19,973 for females. The per capita income for the county was $17,704. About 7.20% of families and 11.40% of the population were below the poverty line, including 13.10% of those under age 18 and 10.10% of those age 65 or over.
Yellowstone National Park - about 4.27% of the park lies within the county. http://factfinder.census.gov/servlet/DTTable?_bm=y&-context=dt&-ds_name=DEC_2000_SF1_U&-CHECK_SEARCH_RESULTS=N&-CONTEXT=dt&-mt_name=DEC_2000_SF1_U_P001&-tree_id=4001&-transpose=N&-redoLog=false&-all_geo_types=N&-geo_id=06000US1604393910&-geo_id=06000US5602993850&-geo_id=06000US5603993905&-geo_id=14000US30031001400&-geo_id=14000US30067000600&-search_results=06000US5602993850&-_showChild=Y&-format=&-_lang=en&-show_geoid=Y