By 1950, the writing was on the road. http://usa.streetsblog.org/2014/04/22/book-excerpt-dead-end-a-look-at-sprawl-and-the-rebirth-of-urbanism/
There was a subtle but profound alteration in the way street corners are built. Curbs no longer meet at right angles; they swing around in broad curves. It became standard even in cities for the curb to start bending back 25 feet from the cross street. On busy suburban roads, the bend begins even farther from the corner. Those on foot must choose between dangerous crossings of broad asphalt expanses and annoying zigzags to where the road narrows. Cars round the turn at highway speed. The simple act of walking down the street is so perilous that pedestrians are sometimes warned to wear reflective clothing, as if they were in the woods during hunting season.
These changes were no mere whim of car-loving traffic engineers. Behind them stood the lobbying might of the trucking industry.
The truckers had fought for decades to put bigger vehicles on the roads, but they were long stymied by the railroads. A major battleground was Pennsylvania, where the Pennsylvania Railroad held sway over the legislature and limits on trucks were especially strict. A few weeks before the 1950 election, the Pennsylvania Motor Truck Association divided $76,000 between the chairpersons of the state Democratic and Republican parties. It was, the association’s treasurer later conceded under oath, like betting on both teams at a baseball game, but he countered that “nothing was hidden, it was all out in the open.”
The truckers gained ground in the 1970s as their old antagonists weakened. But they still faced strenuous opposition from local governments and the American Automobile Association. Even highway engineers objected; they worried that bridges weren’t built to carry the weight of big trucks. Just before the 1974 election, the Truck Operators Nonpartisan Committee made last-minute campaign contributions to 117 congressional candidates from both parties. Six weeks later, the House of Representatives reversed an earlier vote, and weight limits were raised on interstate highways.
In December 1982, the truckers won full victory. The Reagan administration agreed to their demands in exchange for the industry’s acceptance of a tax increase that hit trucks harder than autos. Weight limits were raised again, and state limits on the length and width of trucks were overruled. Tractor-trailers could have trailers up to 48 feet long; soon the limit in most places was 53 feet.
A key provision, not fully understood by critics when the law was rushed through a lame-duck Congress, legalized the big trucks on many local roads as well as on the interstates. Road-builders had a new justification for designs that encourage cars to speed; pedestrians, ignored when the issue was under debate, were the victims. Lanes grew wider; curbs were pushed back at intersections so that extra-long vehicles could make the turn. And, because it was written into the statute, the neighbors had no way to object.