El Dorado is located about 100 miles (160 km) from Little Rock. El Dorado is located at 33°12′49″N 92°39′45″W / 33.21361°N 92.6625°W / 33.21361; -92.6625 (33.213521, -92.662553). in Union County, Arkansas in the southern part of the state. Union County is the largest county in the state of Arkansas and borders the state of Louisiana.