In the 1950s, Detroit planning seemed to be all about expressways. This map from the 1951 Master Plan shows the Edsel Ford (I-94) partially built and the Lodge (M-10) creeping Northwest with dotted lines planning to build many more expressways.
The Master Plan also notes that there was a large park within 20min drive or bus ride for every resident of the city.
DETROITography 
This map shows several proposed-but-never-built limited-access freeways:
Davison / Six Mile / Connor would have been another crosstown artery, connecting the Edsel Ford (I-94) Freeway with the Jeffries (I-96) Freeway, via the pre-existing (completed in 1941) Davison Expressway in Highland Park. Part of the proposed route along McNichols (Six Mile) is now closed to ALL traffic. It’s part of a runway safety area, north of Detroit City (Coleman A. Young International) Airport. The runway safety area became necessary, during the brief period Southwest Airlines 737 jetliners were hosted at the airport.
An extension of the Fisher Freeway along East Vernor, east of Gratiot Avenue, would have connected with another proposed freeway (built through Connor Parkway, south of the airport) at Mack Avenue. If built, this depressed crosstown artery would have crossed through Grand Trunk Western Railroad’s depressed Dequindre Cut line, recently adaptively re-used as today’s Dequindre Cut Greenway rail-trail. At one time, the Dequindre Cut itself was considered for possible conversion into a depressed limited-access freeway. Much of this never-built crosstown route is currently being converted into a commercial forest, by Hantz Woodlands.
An early proposal for the Fisher (I-75) Freeway would probably have taken most of Roosevelt Park, on its way through the pre-existing (completed in 1914) Vernor Highway railroad underpass, adjacent to Detroit’s landmark Michigan Central Station. Construction of this route would also have sacrificed most of the north side of West Fort Street.
The proposed north / south Mound Road (M-53) Expressway would have connected with I-94 near today’s Mt. Elliott Avenue interchange. This new route might have been convenient for Packard employees. The Packard plant closed in 1956.
An early proposal for the Chrysler (I-75) Expressway would have connected its north end to the pre-existing (c. 1920s) south end of the Woodward Avenue “super highway”, just north of Highland Park. As built, today’s I-75 follows Detroit United Railway’s former Stephenson Line (1919-1934) electric interurban route through Hazel Park. The final design adaptively re-used the former trolley line’s 50-mph reverse curves.
The John C. Lodge Expressway, originally designated Interstate Business Spur 696, was completed as planned, connecting with the pre-existing James Couzens / Northwestern Highway near Fenkell (Five Mile) Road. Northwest of Fenkell, the surface-level “super highway” was eventually replaced by today’s walled, limited-access freeway.
Nearly all of Grand River Avenue, northwest of I-94, would have been obliterated by freeway construction.
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