Dakota people lived and hunted in the area of Blue Earth County, particularly the Sisseton.

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.

The ratification of the Mendota and Traverse des Sioux treaties in 1851 effectively forced the eastern Dakota to move to nearby reservations.

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 southeasterly along the western part of the county's northern boundary line.

It is joined by the Blue Earth River, which flows northerly through the western central part of the county.

The Watonwan River flows northwesterly through the northeastern part of the county, discharging into the Blue Earth.

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

Blue Earth County is considered a college town[20] due to the presence of Minnesota State University in Mankato.