New York Subway Extension Begins Service

August 20, 1904 saw the Interborough Rapid Transit Company commence operations on the initial segment of the New York City Subway's Broadway line extension, linking City Hall to 145th Street. Designed by chief engineer William Barclay Parsons, the electrified system used innovative cast-iron tunnels and third-rail power, overcoming challenges like groundwater and dense urban construction. This milestone transformed daily commuting for thousands, reducing reliance on elevated lines and horse-drawn transport while accelerating the city's northward expansion. Key figures included financier August Belmont Jr. and Mayor George B. McClellan. The event cemented New York's status as a global transit leader and laid groundwork for the world's largest subway network, still serving millions daily.