Highway 99 serves as an east–west route in south-central Minnesota between Nicollet, St. Peter, Cleveland, Le Center, and Faribault.

Highway 99 follows Minnesota Avenue for 16 blocks in the city of St. Peter.

Highway 99 is also known as Derrynane Street in the city of Le Center.

[1] It was posted in 1934 and included parts of what were previously State Highways 7 and 21.

A shortcut heading northeast to Le Center was begun in 1953[7] and completed by 1956.