El Dorado is Spanish and means "the gilded one" and the town was maybe named by its first resident, Matthew F. Rainey. According to saying he was an adventurer who's wagon, one day in 1843, broke down in south east Arkansas. Since he couldn't find replacements parts to mend the wagon he had to sell all his possessions. The sale went well, so he decided to open a shop there. Not long after that the new little town was chosen to be Union County's new county seat. El Dorado was incorporated in 1851. At this time cotton growers started to settle in El Dorado and build up plantations. From 1890 to 1920 El Dorado grew from a population of 455 to about 4 000. In 1921 however, oil was found just south of El Dorado and over the next few weeks El Dorado's population grew to more than 20 000. Just ten months after oil was found, 460 wells had been drilled already and 10 million barrels of oil had been pumped up. After the boom El Dorado tried to become a real town, not just an oil camp. A down town was built and the El Dorado-Union County attracts visitors to this day.