# Blue Earth County, Minnesota *County in Minnesota, United States* Blue Earth County is one of the counties of [[Minnesota]]. Its seat is [[Mankato]], and it belongs to the Mankato metropolitan area.[^1] The 2020 census counted 69,112 residents.[^1] The county takes its name from the Blue Earth River and from deposits of blue-green clay once visible along that river's banks.[^1] The county was formed on March 5, 1853, when the [[Minnesota Territory]] was divided. It was assembled from parts of Dakota County and from free territory.[^2] Under a February 27, 1855 exchange, the Winnebago (Ho-Chunk) gave up 897,900 acres of reservation land near Long Prairie and received 200,000 acres on the Blue Earth River.[^2] The county lies near the Lower Sioux reservation, established in 1858. Wikipedia's account traces the Dakota War of 1862 to starvation on that reservation and to government annuities that did not arrive on time.[^2] ## History The [[Dakota]] lived and hunted in the area, the Sisseton in particular.[^2] Pierre-Charles Le Sueur, a French explorer and one of the first Europeans in the region, reached the point where the Minnesota and Blue Earth Rivers meet. He tried without success to mine copper from the blue-green clay that the Dakota used as paint.[^2] France held the area until the Louisiana Purchase transferred it to the United States in 1803.[^2] After Minnesota was organized as a territory in 1849, the territorial government turned its attention to settling the river valley.[^2] In 1850 a steamboat from St. Paul made the first trip up the [[Minnesota River]] to the Blue Earth River. Two of its passengers, P. K. Johnson and Henry Jackson, went ashore and became the first Euro-American settlers at what is now Mankato.[^2] The treaties of Traverse des Sioux and [[Mendota]] were ratified in 1851 and, in effect, compelled the eastern Dakota to relocate to nearby reservations.[^2] The territory was divided on March 5, 1853, creating the county.[^2] Territorial [[governor]] [[Alexander Ramsey]] appointed its first officials. The county's first election followed in October 1853, and 22 ballots were cast.[^2] On February 27, 1855, the Winnebago (Ho-Chunk) ceded 897,900 acres (363,400 ha) of their reservation near Long Prairie. In exchange they received 200,000 acres (81,000 ha) on the Blue Earth River, and they relocated there on May 24, 1855.[^2] According to Wikipedia's account, their farming succeeded to the point that neighboring settlers wanted the land.[^2] The Lower Sioux reservation, near the county, was created in 1858. Wikipedia's account attributes the Dakota War of 1862 to starvation on the reservation and to the late arrival of government annuities.[^2] ## Geography Along the western stretch of the county's northern boundary, the [[Minnesota River]] runs southeast. The Blue Earth River flows north through the west-central county and joins it there.[^3] The Watonwan River runs northwest across the northeastern county and empties into the Blue Earth.[^3] In the southeast, the Little Cobb River flows northwest to meet the Cobb River, which runs north through the lower county into the Blue Earth. The Le Sueur River also crosses the southeast, flowing west-northwest to the Blue Earth.[^3] Outside built-up areas and runoff-carved ground, the gently rolling land is used mostly for farming. It falls generally toward the north, and the southwest corner stands at 1,086 ft (331 m) above sea level.[^3] The total area is 766 square miles (1,980 km²). Land accounts for 748 square miles and water for 18 square miles, or 2.3%. The county contains more than 30 lakes.[^3] Wooded areas sometimes called the "big woods" lie in the northeast along the rivers there. Most of the county is grassland prairie, with scattered wet prairie, and oak openings and brushland appear near some rivers.[^3] ### Major highways The county is served by U.S. Highways 14 and 169 and by Minnesota State Highways 22, 30, 60, 68 and 83.[^3] ## Climate and weather Mankato's recent average temperatures run from a January low of 5 °F (−15 °C) to a July high of 83 °F (28 °C).[^4] The record low, −35 °F (−37 °C), dates from February 1996, and the record high, 107 °F (42 °C), dates from August 1988.[^4] Average monthly precipitation ranges from 0.78 inches (20 mm) in February to 5.09 inches (129 mm) in June.[^4] ## Demographics ### 2020 census The 2020 census recorded 69,112 residents and a median age of 32.3 years. Of these residents, 20.3% were under 18 and 15.1% were 65 or older.[^5] There were 100.5 males per 100 females, and 98.2 males per 100 females among adults.[^5] The census reported the population as 84.2% White, 5.7% Black or African American, 2.7% Asian, 0.4% American Indian and Alaska Native, and under 0.1% Native Hawaiian and Pacific Islander. A further 1.8% reported some other race and 5.1% reported two or more races. Hispanic or Latino residents, of any race, made up 4.7%.[^5] About two-thirds of residents (66.4%) lived in urban areas and 33.6% in rural areas.[^5] The county had 27,193 households. Children under 18 lived in 26.0% of them, and 42.0% were married-couple households.[^5] Of 29,169 housing units, 6.8% stood vacant. Owners occupied 61.5% of occupied units and renters 38.5%.[^5] ### 2000 census In 2000 the census recorded 55,941 people in 21,062 households, including 12,616 families. Density was 74.8 persons per square mile (28.9/km²).[^6] There were also 21,971 housing units, an average of 29.4 per square mile.[^6] ## Communities **Cities:** Amboy, Eagle Lake, Good Thunder, Lake Crystal, Madison Lake, Mankato, Mapleton, Minnesota Lake (partial), North Mankato (partial), Pemberton, Saint Clair, Skyline and Vernon Center.[^7] **Census-designated place:** Garden City.[^7] **Unincorporated communities:** Cambria, Marysburg, Perth and Smiths Mill.[^7] **Townships:** Beauford, Butternut Valley, Cambria, Ceresco, Danville, Decoria, Garden City, Jamestown, Judson, Le Ray, Lime, Lincoln, Lyra, Mankato, Mapleton, McPherson, Medo, Pleasant Mound, Rapidan, Shelby, South Bend, Sterling and Vernon Center.[^7] ## Government and politics From 1952 through the most recent election in the source, the county backed the presidential winner 16 times in 19 contests. It voted for the losing candidate in 1960, 1988 and 2004.[^8] ## In the Minnesota record ### Who - Pierre-Charles Le Sueur, a French explorer, was one of the first Europeans in the area.[^2] - P. K. Johnson and Henry Jackson were the first Euro-American settlers, at present-day Mankato.[^2] - Alexander Ramsey, as territorial governor, appointed the county's first officials.[^2] ### When - 1851: the Mendota and Traverse des Sioux treaties were ratified.[^2] - March 5, 1853: the county was created by division of the Minnesota Territory.[^2] - October 1853: the first county election was held.[^2] - February 27, 1855: the Winnebago (Ho-Chunk) cession took place. They relocated to the Blue Earth River on May 24, 1855.[^2] - 1858: the Lower Sioux reservation was created near the county.[^2] - 1862: the Dakota War took place.[^2] ### Where - The Blue Earth River joins the Minnesota River along the county's northern boundary.[^3] The county lies near the Lower Sioux reservation.[^2] ### How much - In the Winnebago exchange, 897,900 acres (363,400 ha) were ceded for 200,000 acres (81,000 ha) on the Blue Earth River.[^2] - The county covers 766 square miles, 2.3% of it water.[^3] ### How many - 22 ballots were cast at the first county election in 1853.[^2] - The county had 69,112 residents at the 2020 census and 55,941 at the 2000 census.[^5][^6] ## Notes [^1]: Wikipedia contributors, *Blue Earth County, Minnesota*, lead section (revision 1375323765, retrieved 2026-10-25, CC BY-SA 4.0) — 2020 population 69,112; seat Mankato; namesake; Mankato metropolitan area. https://en.wikipedia.org/wiki/Blue_Earth_County,_Minnesota [^2]: Wikipedia contributors, *Blue Earth County, Minnesota*, History section (revision 1375323765, retrieved 2026-10-25) — Dakota occupation, Le Sueur, 1803 transfer, 1849–1851 settlement and treaties, creation March 5, 1853, first officials and election, 1855 Winnebago cession, Lower Sioux reservation (1858), Dakota War of 1862. https://en.wikipedia.org/wiki/Blue_Earth_County,_Minnesota [^3]: Wikipedia contributors, *Blue Earth County, Minnesota*, Geography section (revision 1375323765, retrieved 2026-10-25) — rivers, terrain, elevation, area, lakes, vegetation, major highways. https://en.wikipedia.org/wiki/Blue_Earth_County,_Minnesota [^4]: Wikipedia contributors, *Blue Earth County, Minnesota*, Climate and weather section (revision 1375323765, retrieved 2026-10-25) — Mankato temperature and precipitation ranges and records. https://en.wikipedia.org/wiki/Blue_Earth_County,_Minnesota [^5]: Wikipedia contributors, *Blue Earth County, Minnesota*, Demographics, 2020 census (revision 1375323765, retrieved 2026-10-25) — population, age, sex ratio, census racial composition, urban/rural split, households, housing. https://en.wikipedia.org/wiki/Blue_Earth_County,_Minnesota [^6]: Wikipedia contributors, *Blue Earth County, Minnesota*, Demographics, 2000 census (revision 1375323765, retrieved 2026-10-25) — 55,941 people, 21,062 households, 12,616 families, density, 21,971 housing units. https://en.wikipedia.org/wiki/Blue_Earth_County,_Minnesota [^7]: Wikipedia contributors, *Blue Earth County, Minnesota*, Communities section (revision 1375323765, retrieved 2026-10-25) — cities, census-designated place, unincorporated communities, townships. https://en.wikipedia.org/wiki/Blue_Earth_County,_Minnesota [^8]: Wikipedia contributors, *Blue Earth County, Minnesota*, Government and politics section (revision 1375323765, retrieved 2026-10-25) — presidential voting record since 1952. https://en.wikipedia.org/wiki/Blue_Earth_County,_Minnesota