Well, the GM Streetcar Conspiracy was real.

Aside from that, though, I don’t think it really matters whether other conspiracies existed or not. The same outcome of car-dependency and suburban sprawl was a fait accompli back then because of:

• The prevailing attitudes of Modernist urban planners – look at the Garden City Movement, Le Corbusier’s Ville Radieuse, Frank Lloyd Wright’s Broadacre City, etc.

• The Federal Housing Authority (created in 1934) giving those Modernist ideas the force of law, via things like the 1938 technical bulletin Planning Profitable Neighborhoods (pages 12 & 18) directing developers to prefer suburban strip malls to traditional “main street” commercial development, the 1936 Planning Neighborhoods for Small Houses directing developers to ditch the street grid in favor of insular subdivisions connected only via arterial roads, and, infamously, the Underwriting Manual that penalized traditional development via redlining,

• The prevailing attitude of the public, who were (a) justifiably fed up with the squalor of early-20th-century cities, (b) thoroughly enthralled by the mid-century “American Dream” (read: single-family house with a white picket fence etc.) and car-culture (‘freedom of the open road’, drive-ins, cars as status symbols, etc. – helped along by things like GM’s Futurama, of course), and last but not least, (c) racist AF and engaging in White Flight.

The Suburban Experiment was inevitable because of the above factors, regardless of any collusion between GM and Standard Oil. Besides, since their interests were aligned anyway, if they did collude they probably just agreed to do the same things they already were going to do to begin with.

(By the way: I could’ve sworn I read or heard something somewhere about Frank Lloyd Wright himself being involved with the establishment of the FHA and maybe even having a hand in writing some of the publications I cited, but for the life of me I can’t find the reference anymore. Anybody else know anything about it?)