Derby is a city in Sedgwick County, Kansas, United States. Formerly known as El Paso, it is a suburb of Wichita. As of the 2010 census, the city population was 22,158. As of 2008 the population was estimated at 22,517, making it the 17th largest city in the state of Kansas. Derby was recently named one of the "10 Best Towns for Families" by Family Circle magazine.
In 1871, the town of El Paso was laid out and platted. In 1880, the Santa Fe Railway changed the name of the town to Derby.
Derby is located at 37°33′9″N 97°15′41″W / 37.5525°N 97.26139°W / 37.5525; -97.26139 (37.552407, -97.261492). According to the United States Census Bureau, the city has a total area of 7.5 square miles (19.3 km²), of which, 7.4 square miles (19.3 km²) of it is land and 0.13% is water.