Blue Earth County, Minnesota

Dakota people lived and hunted in the area of Blue Earth County, particularly the Sisseton.^[4] French explorer Pierre-Charles Le Sueur was an early European explorer in this area, arriving where the Minnesota and Blue Earth Rivers meet. He made an unsuccessful attempt to mine copper from the blue-green clay the Dakota used as paint.^[5] The area remained under French control until 1803 when it passed to the United States in the Louisiana Purchase.

When Minnesota became a territory in 1849, the territorial government became interested in settling the river valley. In 1850 the first steamboat trip, starting in St. Paul, traveled on the Minnesota River and came to the Blue Earth River. The first Euro-American settlers, P. K. Johnson and Henry Jackson, debarked and settled in present-day Mankato. The ratification of the Mendota and Traverse des Sioux treaties in 1851 effectively forced the eastern Dakota to move to nearby reservations.

Blue Earth County was created after a division of the Minnesota Territory on March 5, 1853, from portions of Dakota County and free territory. It was named for the Blue Earth River.^[6] The first government officials were appointed by Alexander Ramsey, the territorial governor. That October the first election was held, with 22 ballots being taken.

On February 27, 1855, the Winnebago (Ho-Chunk) ceded 897,900 acres (363,400 ha) of their reservation near Long Prairie in exchange for 200,000 acres (81,000 ha) on the Blue Earth River. On May 24, 1855, they relocated and became so successful at farming that neighboring settlers coveted their land.

Blue Earth County is near the Lower Sioux reservation, which was created in 1858. Starvation on the reservation and the lack of timely arrival of government annuities led to the Dakota War of 1862, followed by removal of all Native Americans from the county.^[7] In 1868 the railroad's arrival promoted the county's growth and development by bringing immigrants and goods to the area.

The Minnesota River flows southeast along the western part of the county's northern boundary. It is joined by the Blue Earth River, which flows north through the western central part of the county. The Watonwan River flows northwest through the northeastern part of the county, discharging into the Blue Earth. The Little Cobb River flows northwest through the southeastern part of the county, meeting with the Cobb River, which flows north through the lower part of the county into the Blue Earth River. The Le Sueur River also flows west-northwest through the southeastern part of the county, discharging into the Blue Earth River.

The county terrain consists of low rolling hills, with the area (except around built-up zones, and in areas carved by runoff) devoted to agriculture.^[9] It slopes generally to the north. Its southwest corner is 1,086 ft (331 m) above sea level.^[10][11]

The county has an area of 766 square miles (1,980 km²), of which 748 square miles (1,940 km²) is land and 18 square miles (47 km²), or 2.3%, is water.^[12] The Blue Earth River and Le Sueur River flow through part of the county. The land surface is relatively flat, with over 30 lakes. There are many "closed forest savannas" that some call the "big woods" in the county's northeast. The rivers that flow out of the northeast are surrounded by these woods. Most of the county is grassland prairie but scattered parts are wet prairie. Some spots that surround the rivers are oak openings and barren brushland.

In recent years,^[when?] average temperatures in the county seat of Mankato have ranged from a low of 5 °F (−15 °C) in January to a high of 83 °F (28 °C) in July, although a record low of −35 °F (−37 °C) was recorded in February 1996 and a record high of 107 °F (42 °C) was recorded in August 1988. Average monthly precipitation ranged from 0.78 inches (20 mm) in February to 5.09 inches (129 mm) in June.^[13]

Blue Earth County has voted for the winning presidential candidate in 16 of the 19 elections since 1952, the exceptions being 1960, 1988, and 2004.

• National Register of Historic Places listings in Blue Earth County, Minnesota