service ("air line" at the time being understood as a nearly-straight and nearly-flat route with distance similar to "as the crow flies") via the Northern Central Railway and Columbia, Pennsylvania. This service was longer than the old route but avoided the transfer in Baltimore. The Union Railroad line opened on July 24, 1873. This route eliminated the transfer in Baltimore. Pennsy officials contracted with both the Union Railroad and the Philadelphia, Wilmington and Baltimore Railroad (PW&B) for access to this line. The Pennsy's New York–Washington trains began using the route the next day, ending Pennsylvania Air Line service. In the early 1880s, the Pennsylvania acquired a majority of PW&B Railroad's stock. This action forced the Baltimore and Ohio Railroad (B&O) to build the Baltimore and Philadelphia Railroad to keep its Philadelphia access, where it connected with the Reading Railroad for its competing Royal Blue Line passenger trains to reach New York. In 1885, the PRR began passenger train service from New York City via Philadelphia to Washington with limited stops along the route. This service became known as the "Congressional Limited Express." The service expanded, and by the 1920s, the Pennsy was operating hourly passenger train service between New York, Philadelphia and Washington. In 1952, 18-car stainless steel streamliners were introduced on the Morning Congressional and Afternoon Congressional between New York and Washington, as well as the Senator from Boston to Washington. New York-Chicago On July 1, 1869, the Pennsylvania Railroad leased the Pittsburgh, Fort Wayne and Chicago Railway (PFtW&C) in which it had previously been an investor. The lease gave the Pennsy complete control of that line's direct route through northern Ohio and Indiana as well as entry into the emerging rail hub city of Chicago, Illinois. Acquisitions along the PFtW&C: Erie and Pittsburgh Railroad, Cleveland and Pittsburgh Railroad, Toledo, Columbus and Ohio River Railroad, and Pittsburgh, Youngstown and Ashtabula Railway gave the Pennsy access to the iron ore traffic on Lake Erie. On June 15, 1887, the Pennsylvania Limited began running between New York and Chicago. This was also the introduction of the vestibule, an enclosed platform at the end of each passenger car, allowing protected access to the entire train. In 1902 the Pennsylvania Limited was replaced by the Pennsylvania Special which in turn was replaced in 1912 by the Broadway Limited which became the most famous train operated by the Pennsylvania Railroad. This train ran from