Source: adapted from American Public Transportation Association,
2012 Public Transportation Fact Book.
Trips by Public Transport in the United States, 1902-2010
The impacts of individual mobility and motorization on urban transportation
have been significant. The outcome was a substantial decline of
the share of public transit in urban mobility to less than 2% of the
passenger miles in the early 21st century. The 1920s saw a dramatic
drop in the share of public transit in urban motorized mobility
as the automobile reached mass production. The only reversal in this
trend was World War II when austerity measures (e.g. rationing of
gasoline) forced urban residents
back to urban transit. As soon as the war was over, the trend resumed.
In the first half of the 20th century, the number of passenger miles
increased in spite of a declining share of public transit due to a large
growth of the urban population. However, from the 1950s there has been
virtually no changes in the level of public transit ridership in the
United States. The question remains about what will be the share of
public transit in future urban mobility.
After a significant decline form the 1950s to the 1970s, transit ridership has
shown limited growth in
the United States, despite continuous investments and improvements.
Variations in ridership are linked with economic cycles of growth and
recession as it is the poorest segment of the population that relies
the most on public transit and is also the most vulnerable segment of
the job market. Light rail systems, from being the dominant form of
urban transit before World War II, have experienced a comeback as many metropolitan areas tried to implement those systems
as less costly transit solutions for lower densities. This is an indication
that most of urban development occurred in suburban areas, which are
poorly serviced by transit systems. Still the overall impact of light
rail is negligible at best and ridership figures are comparatively very
small and are likely to remain so. Heavy rail systems (subways) have
fared better with a ridership that remained constant form the
1960s to the 1980s and that have increased since then.