Lake Madison, South Dakota Demographics & Population 2026

A note before these figures: with a population of 936, Lake Madison's ACS estimates come from a small number of survey responses and carry wide margins of error. Individual percentages below — particularly rates that round to 0% or 100% — are approximations, not precise measurements. See data.census.gov for the published margins of error.

Population Overview

Lake Madison is a small community located in South Dakota, within Lake County. The total population is 936. It ranks as the 88th most populous out of 439 Census-designated places in South Dakota.

Age Demographics

The median age in Lake Madison is 63.2 years. This is 66% higher than the state median of 38.0 years. Only 10.5% of residents are under 18, indicating fewer families with children.

Economy, Income & Housing

The median household income in Lake Madison is $129,191. This is 72% higher than the state median of $75,081. It is also 60% higher than the national median of $80,734. The poverty rate stands at 1.0%. This is 92% lower than the state poverty rate of 11.9%. This exceptionally low poverty rate indicates strong economic prosperity across the community. The unemployment rate is 2.9%. The median home value is $477,800. Housing costs are 86% higher than the state median of $257,400. The home-value-to-income ratio is 3.7x. 90.9% of occupied housing units are owner-occupied. This homeownership rate is 33% higher than the state average of 68.6%.

Race & Ethnicity

Lake Madison has a predominantly White (non-Hispanic) population, comprising 88.9% of all residents.

Education

49.3% of residents aged 25 and older hold a bachelor's degree or higher. This places Lake Madison in the top 10% of all cities in the state for educational attainment. This is 54% higher than the state rate of 31.9%. Nationally, 35.7% of adults hold at least a bachelor's degree. The high school graduation rate (or equivalent) is 99.6%. Notably, 18.4% of adults hold a graduate or professional degree, indicating a highly educated workforce.

Data Sources & Methodology

All demographic data for Lake Madison, South Dakota is sourced from the U.S. Census Bureau's American Community Survey (ACS) 2020–2024 5-Year Estimates. The ACS collects data from approximately 3.5 million households annually and pools five years of responses so that even small communities can be measured, though the margin of error widens as the population falls. Comparisons are made against South Dakota state averages and national averages calculated from the same dataset. Rankings reflect the city's position among all 439 Census-designated places in South Dakota. Read more about how these figures are produced on our methodology page, or visit data.census.gov for official data.