In 1861, the Pennsylvania Railroad gained control of the Northern Central Railway, giving it access to Baltimore, Maryland, and points along the Susquehanna River via connections at Columbia, Pennsylvania, or Harrisburg, Pennsylvania.

On December 1, 1871, the Pennsy leased the United New Jersey Railroad and Canal Company, which included the original Camden and Amboy Railroad from Camden, New Jersey (across the Delaware River from Philadelphia) to South Amboy, New Jersey (across Raritan Bay from New York City), as well as a newer line from Philadelphia to Jersey City, New Jersey, much closer to New York, via Trenton, New Jersey.
Track connection in Philadelphia was made via the Pennsy's Connecting Railway and the jointly owned Junction Railroad.

The Pennsy's Baltimore and Potomac Rail Road opened on July 2, 1872, between Baltimore and Washington, D.C. This route required transfer via horse car in Baltimore to the other lines heading north from the city.
On June 29, 1873, the Baltimore and Potomac Tunnel through Baltimore was completed.
The Pennsylvania Railroad started the misleadingly named Pennsylvania Air Line service via the Northern Central Railway and Columbia, Pennsylvania.
This service was 54.5 miles (87.7 km) 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.
In 1861, the Pennsylvania Railroad gained control of the Northern Central Railway, giving it access to Baltimore, Maryland, and points along the Susquehanna River via connections at Columbia, Pennsylvania, or Harrisburg, Pennsylvania.
On December 1, 1871, the Pennsy leased the United New Jersey Railroad and Canal Company, which included the original Camden and Amboy Railroad from Camden, New Jersey (across the Delaware River from Philadelphia) to South Amboy, New Jersey (across Raritan Bay from New York City), as well as a newer line from Philadelphia to Jersey City, New Jersey, much closer to New York, via Trenton, New Jersey. Track connection in Philadelphia was made via the Pennsy's Connecting Railway and the jointly owned Junction Railroad.
The Pennsy's Baltimore and Potomac Rail Road opened on July 2, 1872, between Baltimore and Washington, D.C. This route required transfer via horse car in Baltimore to the other lines heading north from the city. On June 29, 1873, the Baltimore and Potomac Tunnel through Baltimore was completed. The Pennsylvania Railroad started the misleadingly named Pennsylvania Air Line service via the Northern Central Railway and Columbia, Pennsylvania. This service was 54.5 miles (87.7 km) 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.
Pennsylvania Railroad