Le Sueur is on the Minnesota River, which is a trickling stream compared to the glacial River Warren, which once flowed here. The waters filled the entire valley from the Rush River hills on the west to the hills in the east. The National Minnesota River Valley Scenic Byway passes through Le Sueur.
Le Sueur, named in honor of Pierre Charles Le Sueur, a Frenchman who explored the Minnesota River Valley around 1700, started out as three small settlements named Le Sueur, Middle Le Sueur and Le Sueur City, which were united in 1867 by the Minnesota Legislature. Le Sueur was designated as the county seat of Le Sueur County, a spot it held until 1875. An early resident was Dr. W.W. Mayo who later, with his sons, founded the world-famous Mayo Clinic in Rochester. Green Giant Company was born here in 1903 as the Minnesota Valley Canning Company. In 1950, its name was changed to Green Giant Company. The original plant and warehouse were in operation from 1903 until February, 1995. The main headquarters of the company was located in Le Sueur until 1979 when Green Giant was purchased by the Pillsbury Company. Since then it is now owned by General Mills.