What is light rail?

Light rail is a modern version of streetcars, which were common in American cities in the early part of the 20th century. Light rail runs on conventional rails like regular trains and can travel 60 mph or faster, though they usually go much slower in cities and obey traffic signals like any automobile. Trains are usually two- to three-cars long and the cars are wider and longer than old-time streetcars. Most streetcars were shut down by the 1930s, when Congress stopped allowing utility companies that owned most streetcar lines to write off the costs of providing the service on their taxes. Light rail is different from "heavy" rail — subways — in the smaller number of people that can be carried. Subways usually operate in cities that have the populations to justify a large underground system — such as New York and Washington. Fifty countries have light rail.

Source: David Dobbs of the Texas Association for Public Transportation, Federal Transit Administration

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Cities with light rail systems