Lyman County was created by the Dakota Territorial Legislature in 1873 and organized in 1893. The county was named
for Major W. P. Lyman, a member of the territorial legislature in 1873. Oacoma was the county's earliest town and first
county seat. When Lyman and Jones County separated, Presho and Kennebec were the chief rivals of Oacoma for the honor of
county seat. Following an election, the county seat was moved to Kennebec in 1923.
Geography: Land and Water
As reported by the Census Bureau, the county has a total area of 1,707 square miles (4,421 km2), of which,
1,640 square miles (4,247 km2) of it is land and 67 square miles (174 km2) of it (3.93%) is water.