Sheridan County was named by government officials who prepared the Dakota Territorial map in 1872-1873, after a civil war hero who's name was General Phillip Henry Sheridan.
Although the lines for Sheridan County were drawn in territorial days, Sheridan County was attached to McLean County for judicial purposes. At the general election held on November 3, 1908 in McLean County, the vote was carried by a good majority to divide McLean County and establish Sheridan County effective on January 1, 1909.
As is stated above, Sheridan County was already on the Dakota Territorial Map in 1872-1873, however Sheridan County was formally organized January 1, 1909 after the 1908 general election and has had no boundary changes since.
After the 1908 election establishing Sheridan County, Governor John Burke appointed the county commissioners who then designated the city of McClusky as the temporary county seat. The county commissioners at their first and second meetings appointed the county officials. The city of McClusky furnished a building, rent free, on Main Street for a temporary courthouse until the new courthouse was built.
In the general election of November 8, 1910, the permanent county seat location was voted upon. The city of McClusky won the majority of votes. In 1909 the citizens of McClusky erected the first new courthouse in Sheridan County.
In 1938 expansion was needed for a bigger courthouse. President Franklin D. Roosevelt approved a Works Progress Administration project for Sheridan County in September of 1938. Ground was broken October 24, 1938 to construct a 52' X 88' concrete, steel reinforced courthouse building. It was not until July 1939 when the new courthouse bulding was completed at the final cost of $88,260. The Works Project Administration paid over half of the costs.