transit system in North America after the New York City Transit
Authority, and the Mexico City Metro. The TTC provides public
transit within the City of Toronto. The backbone of its public
transport network is the subway system, as well as a mainly elevated
rapid transit line. The TTC also operates an extensive network of
buses and streetcars.
The Government of Ontario also operates an extensive rail and bus
transit system called GO Transit in the Greater Toronto Area. As of
January 2009[update], GO Transit carries over 205,000 passengers every
weekday on its seven train lines and extensive bus system.
Canada's busiest airport, Toronto Pearson International Airport (IATA:
YYZ), straddles the city's western boundary with the suburban city of
Mississauga. Limited commercial and passenger service is also offered
from the Billy Bishop Toronto City Airport, on the Toronto Islands,
southwest of downtown. Toronto/Buttonville Municipal Airport in
Markham provides general aviation facilities. Toronto/Downsview
Airport, near the city's north end, is owned by de Havilland Canada
and serves the Bombardier Aerospace aircraft factory.
There are a number of municipal expressways and provincial highways
that serve Toronto and the Greater Toronto Area. In particular,
Highway 401 bisects the city from west to east, bypassing the downtown
core. It is one of the busiest highways in the world. The
square grid of major city streets was laid out by the concession road
system, in which each major arterial road is approximately two
kilometres apart from each parallel route.