Lake County is a county in the U.S. state of South Dakota. As of the 2020 census, the population was 11,059. Its county seat is Madison. The county was formed in 1873.

Geography

The terrain of Lake County consists of rolling hills, with the area devoted to agriculture. A tributary of the East Fork Vermillion River flows south-southeastward through the lower western part of the county, and Buffalo Creek flows southeastward from the central part of the county, leaving the county near its southeast corner. The terrain generally slopes to the south, although high points (ca. 1,814' ASL) are found on the north and south boundary lines and points between. Lake County has a total area of 575 sqmi, of which 563 sqmi is land and 12 sqmi (2.1%) is water.

Lakes

Protected areas

Major highways

Adjacent counties

Demographics

2020 census

As of the 2020 census, there were 11,059 people, 4,576 households, and 2,804 families residing in the county. The population density was 19.6 PD/sqmi. There were 5,658 housing units.

2010 census

As of the 2010 census, there were 11,200 people, 4,483 households, and 2,814 families in the county. The population density was 19.9 PD/sqmi. There were 5,559 housing units at an average density of 9.9 /mi2. The racial makeup of the county was 96.2% white, 0.7% Asian, 0.7% American Indian, 0.5% black or African American, 0.8% from other races, and 1.1% from two or more races. Those of Hispanic or Latino origin made up 1.6% of the population. In terms of ancestry, 50.7% were German, 20.6% were Norwegian, 12.4% were Irish, 6.6% were English, 6.2% were Dutch, 5.0% were Danish, and 5.0% were American. Of the 4,483 households, 26.7% had children under the age of 18 living with them, 53.0% were married couples living together, 6.8% had a female householder with no husband present, 37.2% were non-families, and 30.9% of all households were made up of individuals. The average household size was 2.30 and the average family size was 2.88. The median age was 39.9 years. The median income for a household in the county was $45,606 and the median income for a family was $57,753. Males had a median income of $36,370 versus $25,898 for females. The per capita income for the county was $22,447. About 6.5% of families and 12.1% of the population were below the poverty line, including 12.8% of those under age 18 and 8.8% of those age 65 or over.

Communities

City

Towns

Village

Census-designated places

Other unincorporated communities

Townships

Historical townsite

Politics

Lake County voters have voted for Republican Party candidates in 62 percent of national elections since 1964.