Missouri State Route 366 runs east-west in Eastern St. Louis County. This runs from the St. Louis/Shrewsbury City Limits to Interstate 44, at Sunset Hills. It is alos a old alignment of Historical U.S. Rt. 66. MO St Rt 366 passes through the following towns in St. Louis County. Shrewsbury
Marlborough
Webster Grove
Crestwood
Sunset Hills
MO St Rt 366 is not multi-plexed in St. Louis County. MO St Rt 366 intersects the following highways in St. Louis County. Missouri Seocndary State Route P, at Shrewsbury.