United States: Subway
A number of major U.S. cities have underground train systems, including Atlanta, Boston, Chicago, Cleveland, Los Angeles, San Francisco Bay Area, New York, Philadelphia, and Washington, D.C. Many have the most modern and sophisticated types of ticketing machines, some are old enough that humans are still involved. Generally, U.S. subways are clean, well-lighted, and highly efficient and reliable (some of them can be dangerous during off-peak hours, in terms of personal security). Most metros are operated on an integrated fare system and facilitate easy transfers between other modes of transit.
Following is a partial list of subway system information websites for some U.S. cities: