New York Subway Construction Milestone

On August 23, 1904, workers completed critical tunneling under the East River for the IRT's inaugural subway line. Chief engineer William Barclay Parsons directed the use of innovative shield tunneling methods to navigate challenging geology. This segment connected Manhattan to Brooklyn, enabling the full system's opening later that year. The project revolutionized commuting in America's largest city, reduced street congestion, and set standards for underground rail engineering worldwide, influencing subway designs from London to Tokyo.