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I-70 was immortalized in the 1985 "I-70 series" between St. Louis and Kansas City. The series went to Game 7, where the Royals squeaked by, 11-0.
I-170 (cancelled) Maryland
Once proposed to link I-70 with the west end of Baltimore's central business district, all that remains of I-170 is a short freeway, signed US 40, paralleling Franklin Street. The 1.39 mile, 30 foot deep, six-lane freeway opened in 1979, with a median wide enough to accommodate a future rapid rail transit line. Though it's isolated from other freeways, it still serves about 40,000 vehicles per day. 
The I-170 plan dates back to 1969. I-70 would have extended from its current terminus near I-695 to I-95 north of Caton Avenue. I-170 would have extended 2.3 miles from I-70 in West Baltimore to the western edge of the central business district (CBD).  Construction on the existing US 40 segment began in 1975 and finished in 1979. 
In the mid-1980s, the I-70 extension from the western city line inbound was canceled due to community opposition. After that, the portion of I-70 from I-95 to I-170 was still proposed to be built, but would be designated I-595. This plan was canceled in July 1983.  The isolated section of I-170 was redesignated as US 40 in 1989. 
A March 1997 Baltimore Sun article noted a proposal by several neighborhoods to demolish and backfill the US 40 freeway and build homes in place of the hundreds that were removed 20 years before.
11.17 miles ; connects I-270 to I-64 west of St. Louis. Named the Inner Belt Expressway, I-170 was formerly MO 725. Construction finished in the mid-1980s.
The idea of extending I-170 southward, to I-55 and beyond to Lemay Ferry Road, recently surfaced and was dropped. What follows is information from Phil Sutin, who was the St. Louis Dispatch reporter that Westfall called to his office to announce his decision to drop the I-170 south project:
The section north of I-64 was much easier to build, as it paralleled tracks of the Terminal Railroad and had less impact on residential areas. Also, public support for freeways exceeded local opposition in the time the road was built. Also, Ladue, a wealthy city near 170's south end, used construction of the expressway to cut off McKnight Road, then a north-south artery that was bringing traffic and less wealthy people into the city.
Interstate 170 was built in two phases. The first was Interstate 64 to Page Avenue in 1965 through 1967. St. Louis County taxpayers paid for it. Later it was absorbed in the state system and in the 1970s into the Interstate system.
The second was from Page to Interstate 270. The segment was much delayed partly because of a problem with historic houses at the northern end. Former U.S. Rep. Robert A. Young (D-Maryland Heights) got the problems solved and the federal funds flowing for this construction project in his district. The northern section opened in 1983.
Conditions are not as favorable for the proposed 170 extension south. Well-organized middle-class opposition formed in its path. Funds for the $600 million project won't be available for at least 10 years. Facing the prospect of opponents biting at him for 10 years or more, County Executive George "Buzz" Westfall saw the extension as a political liability and dropped the project.