The picturesque, gently rolling hills of northeastern South Dakota were formed by glaciers 20,000 years ago. A French cartographer first mapped the area in 1838, calling it Coteau des Prairies, -French for 'Hills of the Prairies.' On these hills sits Codington County, which got its name from the Reverend G.S. Codington, a traveling preacher based in Watertown. On August 7, 1878, Kampeska was named the first county seat. At the same time, railroad lines were extended from Minnesota into South Dakota, leading to a great influx of population known as the Great Dakota Boom. The rails only went as far as the Big Sioux River, which was east of Kampeska, so by the end of the year, the entire town up and moved to meet the railroad. With its new location came a new name: Watertown. An influx of German and Norwegian settlers in the early 1900s brought Codington County close to its current population of over 25,000

Lists buildings, structures, sites, objects, and districts that possess historical significance as defined by the National Register Criteria for Evaluation, in every state.