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Elmore County, Idaho facts for kids

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Elmore County
Elmore County Courthouse
Elmore County Courthouse
Official seal of Elmore County
Map of Idaho highlighting Elmore County
Location within the U.S. state of Idaho
Map of the United States highlighting Idaho
Idaho's location within the U.S.
Country  United States
State  Idaho
Founded February 7, 1889
Named for The Ida Elmore mines, producer of silver and gold in the 1860s
Seat Mountain Home
Largest city Mountain Home
 • Total 3,101 sq mi (8,030 km2)
 • Land 3,075 sq mi (7,960 km2)
 • Water 26 sq mi (70 km2)  0.8%
 • Total 27,038
 • Estimate 
 • Density 8.7191/sq mi (3.3665/km2)
Time zone UTC−7 (Mountain)
 • Summer (DST) UTC−6 (MDT)
Congressional district 2nd
Canyon Creek Station on the Main Oregon Trail, Idaho
Canyon Creek Station on the Oregon Trail, Elmore County

Elmore County is a county in the U.S. state of Idaho. As of the 2010 census, the population was 27,038. The largest city and county seat is Mountain Home.

Elmore County comprises the Mountain Home, ID Micropolitan Statistical Area, which is also included in the Boise-Mountain Home-Ontario, ID-OR Combined Statistical Area.


Elmore County was established February 7, 1889, with its county seat at Rocky Bar. It is named after the Ida Elmore mines, the area's greatest silver and gold producer of the 1860s, located near Silver City in Owyhee County.

While the Oregon Trail crossed the Snake River in Elmore County, at Three Island Crossing near Glenns Ferry, the significant early settlements of Elmore County were mining settlements located primarily in northern Elmore County surrounding the ghost town of Rocky Bar. Settlement at Rocky Bar commenced in 1863 with the settlement having 560 residents at the Territorial Census of that year. Nearby, Atlanta was settled in 1864. Elmore County north of the Snake River was originally part of Alturas County when it was created in 1864 and Rocky Bar became its county seat. The portion of Elmore County south of the Snake River was within Owyhee County until 1930. A small portion of Ada County was also annexed in 1948, bringing Elmore to its present boundary. The settlement at Rocky Bar was impacted by poor management by mining companies, mining lawsuits, and its geographic remoteness between 1869 and 1880. The Wood River experienced a surge in settlement at Hailey starting in 1880 that led to Rocky Bar's loss of the county seat to Hailey in 1882. Rocky Bar would briefly become a county seat upon the creation of Elmore County in 1889.

A station on the overland stage route, originally named Rattlesnake, was moved west to the railroad line and became Mountain Home. On February 4, 1891, the county seat was moved to Mountain Home.

Construction of what would become Mountain Home Air Force Base was begun in October 1942, 12 miles (19 km) southwest of Mountain Home. The base officially opened in August 1943 as a training base for bombers, and was an operational base under SAC through 1965. It became a fighter base in 1966 under TAC, now the Air Combat Command.

Anderson Ranch Dam is east of Mountain Home on the South Fork of the Boise River. At the time of its completion in 1950, it was the world's highest earthfill dam.


According to the U.S. Census Bureau, the county has a total area of 3,101 square miles (8,030 km2), of which 3,075 square miles (7,960 km2) is land and 26 square miles (67 km2) (0.8%) is water. Elmore County's highest point is Snowyside Peak at 10,651 feet (3,246 m) above sea level, located in the northeast corner of the county in the Sawtooth Wilderness. The lowest elevation in the county is the Snake River in the southwest corner, at less than 2,500 feet (760 m).

Adjacent counties

Major highways

  • I-84.svg Interstate 84
  • US 20.svg US 20
  • US 26.svg US 26
  • US 30.svg US 30
  • ID-51.svg SH-51
  • ID-67.svg SH-67

National protected areas

  • Boise National Forest (part)
  • Sawtooth National Forest (part)
  • Sawtooth National Recreation Area (part)
    • Sawtooth Wilderness (part)
  • Snake River Birds of Prey National Conservation Area (part)


Historical population
Census Pop.
1890 1,870
1900 2,286 22.2%
1910 4,785 109.3%
1920 5,087 6.3%
1930 4,491 −11.7%
1940 5,518 22.9%
1950 6,687 21.2%
1960 16,719 150.0%
1970 17,479 4.5%
1980 21,565 23.4%
1990 21,205 −1.7%
2000 29,130 37.4%
2010 27,038 −7.2%
2020 (est.) 27,448 1.5%
U.S. Decennial Census
1790-1960 1900-1990
1990-2000 2010-2020

2010 census

As of the 2010 United States Census, there were 27,038 people, 10,140 households, and 7,135 families living in the county. The population density was 8.8 inhabitants per square mile (3.4/km2). There were 12,162 housing units at an average density of 4.0 per square mile (1.5/km2). The racial makeup of the county was 82.2% white, 2.8% Asian, 2.7% black or African American, 1.0% American Indian, 0.4% Pacific islander, 6.8% from other races, and 4.1% from two or more races. Those of Hispanic or Latino origin made up 15.2% of the population. In terms of ancestry, 20.4% were German, 13.5% were English, 12.4% were Irish, and 9.0% were American.

Of the 10,140 households, 38.6% had children under the age of 18 living with them, 56.6% were married couples living together, 9.4% had a female householder with no husband present, 29.6% were non-families, and 23.8% of all households were made up of individuals. The average household size was 2.60 and the average family size was 3.11. The median age was 30.0 years.

The median income for a household in the county was $43,089 and the median income for a family was $50,840. Males had a median income of $34,126 versus $25,999 for females. The per capita income for the county was $20,388. About 9.2% of families and 12.0% of the population were below the poverty line, including 19.3% of those under age 18 and 7.8% of those age 65 or over.



Census-designated place

  • Mountain Home Air Force Base

Unincorporated communities

Ghost town

See also

Kids robot.svg In Spanish: Condado de Elmore (Idaho) para niños

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