Prior to Amtrak, the Pennsylvanian route was covered by the Duquesne, named after Fort Duquesne in Pittsburgh, and by the Juniata, both trains operated by the Pennsylvania Railroad and from 1968 to 1971 by the PRR's successor, the Penn Central.
The Duquesne had a long history, finally becoming a daily New York–Pittsburgh train on October 25, 1959, numbered 16 eastbound and 25 westbound.
When the Pennsylvania Railroad's successor, Penn Central, was formed in 1968, it continued to operate the Duquesne and the Juniata.

With the start of Amtrak operations on May 1, 1971, the Duquesne was renamed the Keystone and renumbered 42 westbound and 43 eastbound with the first Amtrak timetable on November 14, 1971.
The Keystone was discontinued on April 30, 1972.

The immediate impetus for the Pennsylvanian was the discontinuance of the National Limited, a New York–Kansas City train which had provided service over the corridor.
That train, in turn, was the successor of the famed Spirit of St Louis.
 The Pennsylvanian began on April 27, 1980, as a state-supported daylight train between Philadelphia and Pittsburgh, with connecting service to New York via the Philadelphian (a Clocker) westbound and the Montrealer eastbound.
At the time the Pennsylvanian was inaugurated, the Broadway Limited was departing Pittsburgh at an inconvenient early morning hour.
The new train ran with Amfleet equipment, including a cafe car.
Pennsylvania agreed to pay 20% of the train's costs for the first year, or $580,000, with the state and Amtrak eventually splitting the costs 50/50 by the third year.

Between 1981 and 1983, Pennsylvanian equipment was turned every night to operate a second state-supported train, the Fort Pitt, which ran from Pittsburgh to Altoona.
Amtrak withdrew this train in early 1983 after the Pennsylvania Department of Transportation (PennDOT) declined to continue subsidizing the increased operation.
At the time the Fort Pitt carried 30 passengers per day.
On October 30, 1983, the Pennsylvanian was extended to New York City, eliminating the transfer at Philadelphia.

After significant ridership gains in 1984, PennDOT proposed that a second train be added to the route.
PennDOT and Amtrak would have split the costs evenly.
Amtrak officials were favorable, but budget problems stalled the plan.

In the late 1980s passenger-rail groups urged Amtrak to extend the Pennsylvanian to Cleveland, Ohio.
Proposals included new stations in Sewickley and Beaver Falls.
Pressure increased in 1989 when Amtrak announced the re-routing of the Broadway Limited and Capitol Limited over that same route as part of a restructuring of routes in Indiana.
As part of this change, the Capitol Limited began serving the Cleveland–Pittsburgh route, albeit in the middle of the night.
Amtrak and PennDOT considered two routes for an extended Pennsylvanian: one via Alliance, Ohio (following the route of the Capitol Limited) and one via Youngstown, Ohio (partially following the Broadway Limited) with a new stop in New Castle, Pennsylvania.

On November 7, 1998, Amtrak extended the Pennsylvanian through to Chicago along the route of the Capitol Limited via Toledo, finally bringing a daylight connection to Cleveland.
The Three Rivers continued to run over a different schedule via Akron and Fostoria.
As part of the change Amtrak truncated the eastern end to Philadelphia, enabling the train to complete the run within a single day.
The change was driven by Amtrak's growing mail and express business; Pittsburgh–Philadelphia ridership suffered.
Amtrak returned the Pennsylvanian to the New York–Pittsburgh route on January 27, 2003, citing low ridership and Amtrak's withdrawal from the express freight business.
On November 1, 2004, Amtrak merged the Pennsylvanian and Three Rivers, keeping the latter name with a western terminus in Chicago.
Amtrak had sought $2.5 million in assistance from Pennsylvania to keep both trains running.
On March 8, 2005, Amtrak truncated service to Pittsburgh–New York and restored the Pennsylvanian name to the route.

There is currently no through service west of
Prior to Amtrak, the Pennsylvanian route was covered by the Duquesne, named after Fort Duquesne in Pittsburgh, and by the Juniata, both trains operated by the Pennsylvania Railroad and from 1968 to 1971 by the PRR's successor, the Penn Central. The Duquesne had a long history, finally becoming a daily New York–Pittsburgh train on October 25, 1959, numbered 16 eastbound and 25 westbound. When the Pennsylvania Railroad's successor, Penn Central, was formed in 1968, it continued to operate the Duquesne and the Juniata.
With the start of Amtrak operations on May 1, 1971, the Duquesne was renamed the Keystone and renumbered 42 westbound and 43 eastbound with the first Amtrak timetable on November 14, 1971. The Keystone was discontinued on April 30, 1972.
The immediate impetus for the Pennsylvanian was the discontinuance of the National Limited, a New York–Kansas City train which had provided service over the corridor. That train, in turn, was the successor of the famed Spirit of St Louis.  The Pennsylvanian began on April 27, 1980, as a state-supported daylight train between Philadelphia and Pittsburgh, with connecting service to New York via the Philadelphian (a Clocker) westbound and the Montrealer eastbound. At the time the Pennsylvanian was inaugurated, the Broadway Limited was departing Pittsburgh at an inconvenient early morning hour. The new train ran with Amfleet equipment, including a cafe car. Pennsylvania agreed to pay 20% of the train's costs for the first year, or $580,000, with the state and Amtrak eventually splitting the costs 50/50 by the third year.
Between 1981 and 1983, Pennsylvanian equipment was turned every night to operate a second state-supported train, the Fort Pitt, which ran from Pittsburgh to Altoona. Amtrak withdrew this train in early 1983 after the Pennsylvania Department of Transportation (PennDOT) declined to continue subsidizing the increased operation. At the time the Fort Pitt carried 30 passengers per day. On October 30, 1983, the Pennsylvanian was extended to New York City, eliminating the transfer at Philadelphia.
After significant ridership gains in 1984, PennDOT proposed that a second train be added to the route. PennDOT and Amtrak would have split the costs evenly. Amtrak officials were favorable, but budget problems stalled the plan.
In the late 1980s passenger-rail groups urged Amtrak to extend the Pennsylvanian to Cleveland, Ohio. Proposals included new stations in Sewickley and Beaver Falls. Pressure increased in 1989 when Amtrak announced the re-routing of the Broadway Limited and Capitol Limited over that same route as part of a restructuring of routes in Indiana. As part of this change, the Capitol Limited began serving the Cleveland–Pittsburgh route, albeit in the middle of the night. Amtrak and PennDOT considered two routes for an extended Pennsylvanian: one via Alliance, Ohio (following the route of the Capitol Limited) and one via Youngstown, Ohio (partially following the Broadway Limited) with a new stop in New Castle, Pennsylvania.
On November 7, 1998, Amtrak extended the Pennsylvanian through to Chicago along the route of the Capitol Limited via Toledo, finally bringing a daylight connection to Cleveland. The Three Rivers continued to run over a different schedule via Akron and Fostoria. As part of the change Amtrak truncated the eastern end to Philadelphia, enabling the train to complete the run within a single day. The change was driven by Amtrak's growing mail and express business; Pittsburgh–Philadelphia ridership suffered. Amtrak returned the Pennsylvanian to the New York–Pittsburgh route on January 27, 2003, citing low ridership and Amtrak's withdrawal from the express freight business. On November 1, 2004, Amtrak merged the Pennsylvanian and Three Rivers, keeping the latter name with a western terminus in Chicago. Amtrak had sought $2.5 million in assistance from Pennsylvania to keep both trains running. On March 8, 2005, Amtrak truncated service to Pittsburgh–New York and restored the Pennsylvanian name to the route.
There is currently no through service west of
Pennsylvanian (train)