Jefferson County, Montana

administration
Jefferson County Courthouse in Boulder, listed on NRHP No. 80002422
US state :	Montana
Administrative headquarters :	Boulder
Foundation :	1864
Demographics
Residents :	11,406 (2010)
Population density :	2.7 inhabitants / km ²
geography
Total area :	4296 km²
Water surface :	6 km²
map

Jefferson County is a county in the state of Montana in the United States . The county seat is in Boulder . The county is named after former President Thomas Jefferson .

geography

The county is located in mid-southwest Montana, about 70 km to the south and west of Idaho and borders clockwise on the counties: Lewis and Clark County , Broadwater County , Gallatin County , Madison County , Silver Bow County , Deer Lodge County and Powell County .

history

Seven buildings and sites in the county are on the National Register of Historic Places (as of February 8, 2018).

Demographic data

growth of population
Census	Residents	± in%
1870	1531	-
1880	2464	60.9%
1890	6026	144.6%
1900	5330	-11.5%
1910	5601	5.1%
1920	5203	-7.1%
1930	4133	-20.6%
1940	4664	12.8%
1950	4014	-13.9%
1960	4297	7.1%
1970	5238	21.9%
1980	7029	34.2%
1990	7939	12.9%
2000	10,049	26.6%
2010	11,406	13.5%
Before 1900 1900–1990 2000 + 2010 Jefferson County's age pyramid (as of 2000)

View over Boulder as seen from Interstate 15

According to the 2000 census , the county had 10,049 people. There were 3,747 households and 2,847 families. The population density was 2 people per square kilometer. The racial the population was composed of 96.07% White, 0.14% African American, 1.26% Native American, 0.42% Asian, 0.07% Pacific Islander, and 0.38% other races Groups; 1.66% were from two or more races. Hispanic or Latino of any race was 1.48% of the population.

Of the 3,747 households, 35.60% had children and adolescents under the age of 18 living with them. 67.10% were married couples living together, 5.90% were single mothers. 24.00% were not families. 20.20% are single households and 7.30% have someone who is 65 years of age or older. The average household size was 2.62 and the average family size was 3.03.

For the entire county, the population was composed of 27.80% of residents under 18 years of age, 5.20% between 18 and 24 years of age, 26.80% between 25 and 44 years of age, 29.90% between 45 and 64 years of age 10.30% were 65 years of age or over. The average age was 40 years. For every 100 females there were 100.80 males, and for every 100 women aged 18 and over there were 100.40 males.

The median income for a household in the city was $ 41,506 , and the median income for a family was $ 48,912. Males had a median income of $ 34,753 versus $ 25,011 for females. The per capita income was $ 18,250. 9.00% of the population and 6.70% of families are below the poverty line. 10.40% of these were under 18 years of age and 9.60% were 65 years of age or older.