The Codington County Courthouse is located at 14 First Avenue Southeast, Watertown, SD 57201; phone: 605-882-6297.
The earliest recorded visit by Whites into the lands that form Codington County was 1840, with the first permanent settler reportedly arriving in 1871. Railroads often provided the major mode of travel into Dakota Territory. The first railhead in Codington County was established in Watertown in 1873. Regular services began in 1878, forming the subsequent genesis of the "Dakota Boom" for this glacial lakes area trade center.
Created during territorial days from parts of Grant, Hamlin, and Clark counties, Codington County was formally organized in August, 1878, with Kampeska serving as a temporary county seat. Following a county-wide election in October of that same year, Watertown prevailed as the seat of government.