The portion of MetroLink's Cross County Extension south of I-64 runs roughly along the proposed alignment.

[3] The southern portion of I-170 was built using St. Louis County funds in the 1960s through a shallow valley.

[4] Proposals have been made to extend I-170 south beyond its termination at I-64/US 40, and so connect to I-55, I-270, and I-44, and to towns such as Richmond Heights, Brentwood, Maplewood, and Marlbourough.

These towns currently lack direct access to the Interstates, St. Louis Lambert International Airport, South County, and to each other.

Many commuters travel on slower surface streets, such as Hanley Road or River Des Peres Boulevard, raising traffic in Shrewsbury and other residential towns.