Eldorado ( or ) is a city in Saline County, Illinois, United States. The population was 4,122 at the 2010 census, with a 1925 peak of 8,000. Although the city's name is spelled as if it were Spanish, the name was originally "Elder-Reado"—a combination of the last names of the town's two founders, Judge Samuel Elder and Joseph Read. According to legend, a signpainter for the railroad painted the name "Eldorado" on the train depot; as a result, the spelling and pronunciation was forever changed.
In September, 1963, five months before The Beatles' first appearance on The Ed Sullivan Show brought them stardom in the United States, George Harrison performed at the Veterans of Foreign Wars hall in Eldorado with a local band. This was the first performance by a Beatle in the United States. At the time, Harrison and his brother were visiting their sister, Louise, who had recently relocated with her husband to nearby Benton.
At one time there was an extensive maze of railroad tracks that arched out from the town's center. All but one are now replaced with bike trails.
In 1946, the adjacent village of Beulah Heights disincorporated and annexed to Eldorado.
Eldorado was a sundown town until the offensive sign was removed in the 1960s.