The first underground railway in the world was the Metropolitan Railway, now part of the London Underground.[30] London's system was proposed by Charles Pearson, as part of a city improvement plan, after the Thames Tunnel opened. After ten years of discussion, the British Parliament authorized the construction of an underground railway. Construction began in 1860 and was complete in 1863. Steam locomotives were used on the underground route until 1905.[31] The first electric underground railway was the City & South London Railway, also now part of the Underground, which opened in 1890.
The first rapid transit systems in North America were elevated railways like Manhattan's Ninth Avenue Line (1868). The first underground transit line was a short piece of Boston's Green Line, opened in 1897, but this was a streetcar tunnel that only carried rapid transit trains from 1901 to 1908 (when Boston's first new rapid transit tunnel opened).
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The inventor popularly credited with the invention of the pneumatic tube subway is Alfred Beach. Beach received a 1865 patent for a pneumatic transit system (pneumatic tube) for mail and passengers. He also built America's first subway.