El Dorado
- County:
- Union County
- County Seat:
- Yes
- Area (mi²):
- 16.201
- State:
- Arkansas
El Dorado is a city located in Union County, Arkansas. El Dorado has a 2026 population of 16,657. It is also the county seat of Union County. El Dorado is currently declining at a rate of -1.23% annually and its population has decreased by -5.89% since the most recent census, which recorded a population of 17,700 in 2020.