Missouri State Route 21 is a norht-south highway in Southern St. Louis County. This runs from Gravois Road to the St. Louis/Jefferson County Line on Tesson Ferry Road. MO St Rt 21 passes through the following towns in St. Louis County. Lakeshire Green Park MO St Rt 21 is not multi-plexed in St. Louis County. MO St Rt 21 intersects the following highways in St. Louis County. Missouri State Route 30, near Lakeshire.
A junction marker on EB MO St Rt 30. A BGS on WB I-270. A BGS on WB I-270. A BGS on WB I-270. A BGS on EB I-270. NB MO St Rt 21 near Suson Hill Drive. NB MO St Rt 21 north of the Meramec River. MB MO St Rt 21 crossing the Meramec River.
