Missouri State Highway 21 is a highway in eastern
Missouri . Its northern terminus is at
Missouri State Highway 30 in
Affton . Its southern terminus is at the
Arkansas state line (where it continues as
Arkansas State Highway 115 ). In the St. Louis area, it is known as Tesson Ferry Road.
The section through northern
Jefferson County, Missouri was the site of numerous fatal traffic accidents due to the narrow road being unable to handle increased traffic from population growth, and was referred to as "Blood Alley" and "Missouri's Most Dangerous Highway". As a result, the road was rerouted and built to
Freeway grade.
