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Gem County, Idaho facts for kids

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Gem County
Gem County Courthouse
Gem County Courthouse
Official seal of Gem County
Map of Idaho highlighting Gem 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 March 15, 1915
Named for the state nickname, "Gem State".
Seat Emmett
Largest city Emmett
 • Total 566 sq mi (1,470 km2)
 • Land 561 sq mi (1,450 km2)
 • Water 4.8 sq mi (12 km2)  0.8%
 • Total 16,719
 • Estimate 
 • Density 29.539/sq mi (11.405/km2)
Time zone UTC−7 (Mountain)
 • Summer (DST) UTC−6 (MDT)
Congressional district 1st

Gem County is a county in the U.S. state of Idaho. As of the 2010 census, the population was 16,719. The county seat and largest city is Emmett.

Gem County is part of the Boise, ID Metropolitan Statistical Area.

Gem County is home to the Idaho ground squirrel.


Named for the state nickname, "Gem State," the county was established on March 15, 1915, partitioned from Canyon County and Boise County. Fur trappers were in the area as early as 1818, and Alexander Ross explored Squaw Creek in 1824. Prospectors and miners moved through the county in 1862 en route to the gold rush in the Boise Basin around Idaho City, and by the next year irrigation began along the Payette River. Under Washington Territory, the area was part of Idaho County from the time of settlement until the territory south of the Payette River became part of Boise County at its creation in 1863. Picket's Corral, northeast of Emmett was the base of operations for a gang of horse thieves and "bogus dust peddlers" between 1862 and 1864. The Payette Vigilance Committee eliminated the gang, bringing safety for citizens of the area. The act creating Ada County in 1864 established the Ada County boundary common to Boise County as a line from Grimes Creek to Picket's Corral and then north from that point to the existing northern boundary of Boise County, leaving the areas outside of Emmett within Boise County. Jonathan Smith and Nathaniel Martin settled near Emmett about 1862. They established a ferry on the Payette River at Emmett in 1866. On May 31, 1867, a post office was established at the ferry and named Martinsville. Martinsville was renamed Emmettsville on October 31, 1868. Postal officials shortened the name of the post office to Emmett in 1885.

Census data for the area shows Squaw Creek Precinct under Boise County with a population of 30 in 1870. Ada County did not separately return precincts at that census. By 1890, Squaw Creek was split into two precincts. Those precincts were grouped with Horseshoe Bend at the 1890 census. The Emmett precinct contained 479 residents at that time. The Emmett area was transferred to Canyon County at its establishment in 1892. At the 1910 Census, three Emmett area precincts contained a population of 2,601 while three Boise County precincts of Upper Squaw Creek, Lower Squaw Creek, and Pearl contained 1,069 residents.

The Black Canyon diversion dam on the river was built in the early 1920s, east of Emmett.


According to the U.S. Census Bureau, the county has a total area of 566 square miles (1,470 km2), of which 561 square miles (1,450 km2) is land and 4.8 square miles (12 km2) (0.8%) is water. It is the fifth-smallest county in Idaho by area.

Adjacent counties

National protected area

  • Boise National Forest (part)


Historical population
Census Pop.
1920 6,427
1930 7,419 15.4%
1940 9,544 28.6%
1950 8,730 −8.5%
1960 9,127 4.5%
1970 9,387 2.8%
1980 11,972 27.5%
1990 11,844 −1.1%
2000 15,181 28.2%
2010 16,719 10.1%
2020 (est.) 18,703 11.9%
U.S. Decennial Census
1790-1960 1900-1990
1990-2000 2010-2020

2010 census

As of the 2010 United States Census, there were 16,719 people, 6,495 households, and 4,611 families living in the county. The population density was 29.8 inhabitants per square mile (11.5/km2). There were 7,099 housing units at an average density of 12.7 per square mile (4.9/km2). The racial makeup of the county was 93.4% white, 0.6% American Indian, 0.5% Asian, 0.1% Pacific islander, 0.1% black or African American, 3.1% from other races, and 2.2% from two or more races. Those of Hispanic or Latino origin made up 8.0% of the population. In terms of ancestry, 23.2% were German, 19.2% were English, 15.8% were American, and 12.3% were Irish.

Of the 6,495 households, 30.6% had children under the age of 18 living with them, 56.9% were married couples living together, 9.3% had a female householder with no husband present, 29.0% were non-families, and 24.3% of all households were made up of individuals. The average household size was 2.55 and the average family size was 3.01. The median age was 42.9 years.

The median income for a household in the county was $42,794 and the median income for a family was $49,976. Males had a median income of $39,482 versus $31,083 for females. The per capita income for the county was $20,431. About 9.7% of families and 14.7% of the population were below the poverty line, including 17.3% of those under age 18 and 9.3% of those age 65 or over.


As of 2016 the largest self-reported ancestries/ethnicities in Gem County, Idaho were:

Largest ancestries (2016) Percent
English England 19.3%
German Germany 17.9%
Irish Republic of Ireland 11.9%
"American" United States 8.8%
Italian Italy 3.3%
Scottish Scotland 2.4%
Dutch Netherlands 1.1%
French France 2.0%
Swedish Sweden 1.7%
Norwegian Norway 1.1%
Swiss Switzerland 0.9%
Welsh Wales 0.8%

2020 census

Gem County racial composition
(NH = Non-Hispanic)
Race Pop 2010 Pop 2020 % 2010 % 2020
White (NH) 14,898 16,132 89.11% 84.36%
Black or African American (NH) 20 29 0.12% 0.15%
Native American or Alaska Native (NH) 77 124 0.46% 0.65%
Asian (NH) 78 99 0.47% 0.52%
Pacific Islander (NH) 10 20 0.06% 0.1%
Some Other Race (NH) 13 96 0.08% 0.5%
Mixed/Multi-Racial (NH) 287 901 1.72% 4.71%
Hispanic or Latino 1,336 1,722 7.99% 9.0%
Total 16,719 19,123

Note: the US Census treats Hispanic/Latino as an ethnic category. This table excludes Latinos from the racial categories and assigns them to a separate category. Hispanics/Latinos can be of any race.

As of the 2020 United States census, there were 19,123 people, 6,683 households, and 4,585 families residing in the county.



Unincorporated communities

See also

Kids robot.svg In Spanish: Condado de Gem para niños

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