Ada County | |
|---|---|
 James A. McClure Federal Building and U.S. Courthouse in Boise, Idaho. | |
 Seal | |
 Location within the U.S. state of Idaho | |
 Idaho's location within the U.S. | |
| Coordinates: 43°27′N 116°14′W / 43.45°N 116.24°W | |
| Country |  United States |
| State |  Idaho |
| Founded | December 22, 1864 |
| Named for | Ada Riggs |
| Seat | Boise |
| Largest city | Boise |
| Area | |
| • Total | 1,060 sq mi (2,700 km2) |
| • Land | 1,053 sq mi (2,730 km2) |
| • Water | 7.9 sq mi (20 km2) 0.7% |
| Population (2020) | |
| • Total | 494,967 |
| • Estimate (2022) | 518,907  |
| • Density | 470/sq mi (180/km2) |
| Time zone | UTC−7 (Mountain) |
| • Summer (DST) | UTC−6 (MDT) |
| Congressional districts | 1st, 2nd |
| Website | www |
| County Code: 1A | |
Ada County is located in the southwestern part of Idaho, United States. As of the 2020 census, the county had a population of 494,967,[1] which by 2022 was estimated to have risen to 518,907.[2] Ada County is by far the state's most populous county; it is home to 26.8% of the state's population. The county seat and largest city is Boise,[3] which is also the state capital.[4] Ada County is included in the Boise metropolitan area. The Ada County Highway District has jurisdiction over all the local county and city streets, except for private roads and state roads. In the interior Pacific Northwest east of the Cascade Range, Ada County ranks second in population, behind Spokane County, Washington.
- ^ "State & County QuickFacts". United States Census Bureau. Retrieved January 15, 2024.
- ^ "Annual Estimates of the Resident Population for Counties: April 1, 2020 to July 1, 2022". United States Census Bureau. Retrieved January 15, 2024.
- ^ "Find a County". National Association of Counties. Archived from the original on May 31, 2011. Retrieved June 7, 2011.
- ^ "Facts About Idaho". Idaho Department of Commerce. 2011. Archived from the original on September 3, 2011. Retrieved November 10, 2011.