Harding County is a county in the northwestern corner of the U.S. state of South Dakota. As of the 2020 census, the population was 1,311, making it the third-least populous county in South Dakota. Its county seat is Buffalo.

Harding County was established as a county in the Dakota Territory on March 5, 1881, but was not organized at that time. Its name recognized J. A. Harding, who had been Speaker of the House of Dakota Territory. Its boundaries were altered in 1883, in 1889, and in 1894. On November 8, 1898, Harding County was dissolved and its territory assigned to Butte County. However, on November 3, 1908, it was again created (with altered boundaries) from Butte County's area, and on February 17, 1909 its governing organization was completed.

Custer National Forest has its South Dakota portion in Harding County, and South Dakota State University operates the Antelope Range and Livestock Research Station about east of Buffalo.

Geography

Harding County lies at the northwest corner of South Dakota. Its western boundary line abuts the east boundary line of the state of Montana, and its north boundary line abuts the south boundary line of the state of North Dakota. Its terrain consists of high hills, generally sloping to the east. Its highest point is a ridge that runs northwest to southeast near the county's southwest corner, at ASL.

Harding County has a total area of , of which is land and (0.2%) is water. It is the fourth-largest county in South Dakota by area.

Major highways

  • 20px U.S. Highway 85
  • 20px South Dakota Highway 20
  • 20px South Dakota Highway 79

Adjacent counties

  • Bowman County, North Dakota – north
  • Adams County, North Dakota – northeast
  • Perkins County – east
  • Butte County – south
  • Carter County, Montana – west
  • Fallon County, Montana – northwest

Protected areas

  • Custer National Forest (partial)
  • Gardner Lake State Game Production Area
  • Mallula State Game Production Area
  • State Experiment Farm and Antelope Reserve

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The population density was .

The racial makeup of the county was 92.6% White, 0.4% Black or African American, 2.2% American Indian and Alaska Native, 0.0% Asian, 0.8% from some other race, and 4.0% from two or more races. Hispanic or Latino residents of any race comprised 2.4% of the population.

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In the South Dakota Senate Harding is part of the 28th Senate district, which is held by Republican Ryan Maher. In the State House Harding is part of district 28B, which is held by Republican Neil Pinnow.

Communities

Towns

  • Buffalo (county seat)
  • Camp Crook

Unincorporated communities

  • Harding
  • Karinen
  • Ladner
  • Ludlow
  • Ralph
  • Redig
  • Reva