Mass transit in the 19th century, such as animal-powered omnibuses and street cars, was primarily a private enterprise. It played a big role in urbanization.

Mass transit appears in Greek mythology in the form of Charon, who ferries the souls of the dead to the Hades — for a price.

After their invention around the turn of the century, motorized buses became popular in the US and overtook streetcars by the 1920s. Ridership peaked in 1927, fell during the Great Depression, and then reached a second peak in 1946 (presumably as a result of the rationing of gas and materials needed for making cars). Since then, buses have declined in popularity, despite a resurgence in the early 1970s (perhaps due to the oil crisis), replaced by the private automobile.

Surprisingly (to Westerners), mass transit is the main way of getting around in the world. Though private cars dominate in the West, the majority of the world’s population resides in countries where transit is more widely used. By transit, I mean everything from trains to buses to jitneys.

The farebox recovery ratio is the proportion of operating expenses covered by fares. Most systems are funded through a mix of fare revenue and government subsidy, though some systems are completely subsidized and others are completely financed by fares. My interest, naturally, is in the systems that are supported by fares. Not surprisingly, profitable private systems can be found in very dense areas, like Japan and Hong Kong. The MTR in Hong Kong, which operates subways, is one such system.

More good info here.

Extra: great summary of these issues. Also, a somewhat dated paper here.