The Pennsylvania Railroad (PRR) was founded in 1846 and operated continuously through various mergers and acquisitions until 1970 when it filed for bankruptcy. The PRR was the largest railroad by traffic and revenue in the U.S. for the first half of the twentieth century, and was at one time the largest publicly traded corporation in the world.
The PRR rail network extended from Philadelphia to Jersey City. Crossing the Hudson River to Manhattan, however, required passengers to transfer to ferries. After a failed attempt at building a tunnel in 1874, then a bridge in 1895, construction of a pair of single-track tunnels began in 1904. The tunnels were opened in 1910, a decade before the publication of The Age of Innocence, and ran between Weehawken and mid-town Manhattan.