blogTO's Derek Flack describes how Toronto saved the streetcar in North America by simply sticking with this class of vehicles.
At the turn of the 20th century almost every major North American city relied on the streetcar as its primary mode of public transportation. New York would open the first portion of its subway system in 1904, but the demise of trolly-based transportation took place at the hands of the bus more than anything else.
Persistent conspiracy theories allege that the decline of the North American streetcar system can be traced to a plot by General Motors as well as numerous oil and tire companies to spur automobile dependency in the U.S., an urban mythology which has its roots in the very real charges that were brought against GM for monopolizing the sale of buses during the post-Depression period.
Streetcar systems across the States dropped like flies from the late 1930s through to the '50s when the bus rose to dominance as the surface vehicle of choice for public transit in mid-sized American. Even Los Angeles used to be a streetcar town until the early 1960s, when both the Pacific Electric and the Los Angeles Railway ceased operations.
Cities like Chicago, Brooklyn, Boston, Philadelphia and Pittsburgh all made large-scale purchases of President's Conference Committee (PCC) streetcars when they were released in the 1930s, but by 1954 Toronto had the largest fleet on the continent as the TTC purchased used cars from American cities that were retiring the electric railways (e.g. Ceveland, Kansas City, and Cincinnati).
The streetcar was yet to be an endangered species at the halfway point of the century, but its decline was in full swing. Following the release and popularity of the PCC cars, only a handful of U.S. cities updated their fleets with newer rolling stock.