Lyman County

Lyman County is an administrative division in central South Dakota with the Missouri River running along its northern and eastern edges and the White River marking the southern boundary. Several small communities are connected by highways throughout the territory, with Kennebec serving as the county seat for over a century.

The Dakota Territorial Legislature established the county in January 1873 as an organized territory. The name was officially assigned two decades later once formal organization was completed.

The county is home to several Native American reservations and communities, reflecting its important role as a Native American settlement area. The name Kennebec, the county seat, comes from the Kennebec River in Maine, showing how early settlers brought names from their home regions.

Visitors can reach the various communities by car, as several highways cross the territory. It is best to use Kennebec as a base for orientation, as it is the largest center with the most services.

The population peaked in 1910 with over 10,000 residents before declining steadily afterward. This pattern is common across many rural plains counties that experienced settlement booms followed by long-term population decline.

Location: South Dakota

Inception: 1873

Capital city: Kennebec

Shares border with: Hughes County, Hyde County, Buffalo County, Brule County, Charles Mix County, Gregory County, Tripp County, Mellette County, Jones County, Stanley County

Website: http://lymancounty.org

GPS coordinates: 43.90000,-99.85000

Latest update: December 10, 2025 16:02