As inherited from Penn Central in 1971, most service on the Springfield Line consisted of unnamed Budd Rail Diesel Car shuttles that connected with Northeast Corridor trains at New Haven, with limited through service to New York City.
In 1980, Connecticut invested $12 million to improve service on the line.
North Haven station was opened on October 25, 1980, and other stations were renovated.
A new fleet of 12 Budd SPV-2000 diesel railcars allowed an increase to 12 daily round trips under the Connecticut Valley Service name (plus two through trips) at that time.
However, service was cut in half in 1981 after ridership failed to increase.

On January 12, 1986, Amtrak pulled the unreliable SPVs from the line and replaced them with Amfleet coaches pulled by diesel locomotives.
North Haven and Enfield stations were closed on October 25, 1986 due to low ridership.
As New Haven was the northern limit of electrification on the Northeast Corridor, New York–Boston trains changed between electric and diesel locomotives at the station.
The passenger coaches of Springfield shuttle trains were attached to southbound trains during the engine change, and detached from northbound trains; this eliminated the need for passengers to change trains.
The Connecticut Valley Service name was soon dropped, and shuttle trains were named in timetables as sections of their connecting trains.
The elimination of the second track on the line beginning in 1990 sharply reduced capacity, limiting frequencies to four daily shuttle round trips plus several through trips.

On October 28, 1995, most Northeast Corridor service including the shuttle trains were consolidated under the NortheastDirect brand.
Electrification was extended to Boston in 2000, and engine changes were eliminated over the next two years.
The cumbersome split/merge procedure was abandoned in favor of dedicated shuttle trains with cross-platform connections to through trains.
The shuttle trains began to use Former Metroliner cab cars, which had become available when replaced by new equipment on West Coast routes.
This allowed them to operate in push–pull format, eliminating the need to wye or loop the trainsets at New Haven and Springfield.
The NortheastDirect name was dropped in September 2001; Northeast Corridor trains became the Acela Regional (later Regional then Northeast Regional), while the shuttle trains became unnamed.
They remained unnamed until 2019 when they received the Hartford Line and Valley Flyer names
As inherited from Penn Central in 1971, most service on the Springfield Line consisted of unnamed Budd Rail Diesel Car shuttles that connected with Northeast Corridor trains at New Haven, with limited through service to New York City. In 1980, Connecticut invested $12 million to improve service on the line. North Haven station was opened on October 25, 1980, and other stations were renovated. A new fleet of 12 Budd SPV-2000 diesel railcars allowed an increase to 12 daily round trips under the Connecticut Valley Service name (plus two through trips) at that time. However, service was cut in half in 1981 after ridership failed to increase.
On January 12, 1986, Amtrak pulled the unreliable SPVs from the line and replaced them with Amfleet coaches pulled by diesel locomotives. North Haven and Enfield stations were closed on October 25, 1986 due to low ridership. As New Haven was the northern limit of electrification on the Northeast Corridor, New York–Boston trains changed between electric and diesel locomotives at the station. The passenger coaches of Springfield shuttle trains were attached to southbound trains during the engine change, and detached from northbound trains; this eliminated the need for passengers to change trains. The Connecticut Valley Service name was soon dropped, and shuttle trains were named in timetables as sections of their connecting trains. The elimination of the second track on the line beginning in 1990 sharply reduced capacity, limiting frequencies to four daily shuttle round trips plus several through trips.
On October 28, 1995, most Northeast Corridor service including the shuttle trains were consolidated under the NortheastDirect brand. Electrification was extended to Boston in 2000, and engine changes were eliminated over the next two years. The cumbersome split/merge procedure was abandoned in favor of dedicated shuttle trains with cross-platform connections to through trains. The shuttle trains began to use Former Metroliner cab cars, which had become available when replaced by new equipment on West Coast routes. This allowed them to operate in push–pull format, eliminating the need to wye or loop the trainsets at New Haven and Springfield. The NortheastDirect name was dropped in September 2001; Northeast Corridor trains became the Acela Regional (later Regional then Northeast Regional), while the shuttle trains became unnamed. They remained unnamed until 2019 when they received the Hartford Line and Valley Flyer names
Hartford Line (Amtrak)