Since the 1940s, there has been a broad shift away from public transit across the U.S., and service has declined in many cities, including New York, Boston, Denver, Orlando and St. Louis. A look back at the last national mass transit boom helps explain the challenges that confront modern transit agencies.

Starting in the 19th century, transit companies worked closely with real estate developers to develop "streetcar suburbs" for a growing population. The companies kept fares low, thanks to corporate consolidation, government regulation and thrifty management.

During World War II, producing weapons and supplies for troops fighting abroad became the nation's top priority. Gasoline, tires and autos were strictly rationed, so most commuters had few ways to get to work other than public transit.

In Baltimore, for example, people could ride a streetcar anywhere in the city in 1943 for 10 cents. With wartime production booming, the city's Baltimore Transit Company packed customers into every streetcar and bus it could find.

Here and in other racially divided northern and border cities, public transit was an integrated space that was fundamental to social mobility. Tens of thousands of Black workers, part of the Great Migration from southern to northern states, enjoyed access to comparatively excellent citywide networks of streetcars, buses and electric trolleybuses.

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