El Dorado (pronounced to rhyme with 'tornado' (IPA: [εl doˈreɪdoʊ] or [εl dəˈreɪdə])) is a city in Union County, Arkansas, USA. According to 2006 Census Bureau estimates, the population of the city is 20,467. The city is the county seat of Union County, and home to the headquarters of Murphy Oil Corporation, Deltic Timber Corporation, and Lion Oil Refinery. The city hosts a community college, South Arkansas Community College ("Southark"), as well as a symphony and an arts center. Most recently, El Dorado has become a community of education with the January 2007 announcement by Murphy Oil Corporation of the El Dorado Promise (www.eldoradopromise.com). The El Dorado Promise is a scholarship program that allows all El Dorado High School graduates who have been at the school since at least the ninth grade, to attend any college in the country of their choice on Murphy's dime.

El Dorado is the site for several annual events, including the Mayhaw Festival hosted by the South Arkansas Historical Foundation the first Saturday of each May (with a crawfish boil the same weekend), a Fantastic Fourth Celebration during July (including a 5k run, an antique car show, and fireworks), the SouthArk Outdoor Expo in September, the two-day MusicFest in October (with pop, rock, blues, and country performers, among other events), and various winter holiday events, including the largest Christmas parade in the state. The above mentioned Crawfish Boil has become so much more. It now hosts a "Battle of the Bands", a Bike show/one day motorcycle rally, a motorcycle parade, a Pool tournament, and much more. The official name of the event is "Bugs, Bands, and Bikes".