[7] When the Metroliner high-speed program had begun two years earlier, the state had attempted to capitalize on the opportunity to purchase upgraded rolling stock for the 600-series trains.

On August 30, 1966, Governor William Scranton of Pennsylvania announced plans to purchase 11 Metroliners capable of 80 mph (130 km/h) service to replace the Silverliners then used.

The PRR soon withdrew after complaints from competing Red Arrow Lines and Capitol Trailways, and the HUD grants were later found to be inapplicable to intercity service.

They had slower acceleration than the Silverliners already in service, tended to overheat when making numerous closely spaced stops, and had difficulty climbing the grade out of Suburban Station.

Additionally, the corridor lacked high-level platforms to effectively use the cars, and 15 substations would require expensive modifications.

[citation needed] On March 31, 1971, Penn Central filed with ICC to discontinue the 600-series trains at the conclusion of their contract with SEPTA on June 30.

On April 30, Judge John P. Fullam ordered Penn Central to continue operating the trains and ultimately referred the case to the ICC.

[17] In the late 1970s, NJDOT's new Arrow III railcars arrived several years ahead of the completion of electrification projects to allow their use in New Jersey commuter service.

In April 1978, Amtrak leased 70 of NJDOT's Arrow II cars for use on the Clockers, Keystone Service, and the new Chesapeake.

[19] In late 1980, under pressure from NJDOT, Amtrak returned all but 32 of the Arrows, which quickly created the need to find other rolling stock for the Silverliner Service.

[20] On April 24, 1983, a pair of weekday trains – the 9:54 am arrival and 3:55 pm departure from Suburban Station – were renamed Keystone Executive.

Intended to attract riders from the western end of the corridor, the trains made intermediate stops only at Lancaster, Downingtown, and 30th Street, with a 99-minute schedule.

[24] These one-off stops were gradually dropped: Merion in 1979; 52nd Street and Berwyn in 1980; Radnor and Narberth in 1982; and Bryn Mawr, Overbrook, and Wayne in 1987.

[citation needed] Amtrak and SEPTA opened a station in Exton on November 2, 1981, to serve fast-growing suburban areas.

[20] The Silverliner Service carried over one million passengers in 1980, but ridership was in steep decline due to a variety of factors.

[20] A wreck of the Night Owl four days later took two AEM-7 locomotives out of commission, exacerbating a shortage of electric power available to Amtrak.

The former train stopped only at Lancaster and Paoli between Harrisburg and North Philadelphia; it was intended for long-distance travelers between the East Coast and the Midwest rather than local passengers.

[31] However, its introduction meant that through passengers no longer had to change at Philadelphia or rely on the Broadway Limited, whose on-time performance had plunged to just 6.8% in 1973.

[30]: 75 At the same time, a pair of Clockers, the westbound Keystone and eastbound Big Apple, were extended to Harrisburg on weekends.

[38] Amtrak discontinued its stops at Whitford and Malvern (both served only by a single round trip) on April 5, 1998, reducing the number of suburban stations shared by SEPTA and Keystone Service trains to four.

This included the restoration of fully electrified service, as well as track improvements for a top speed of 110 miles per hour (180 km/h).

[40] Later improvements aimed to develop a sealed corridor without public at-grade crossings, which would allow future speed increases to 125 miles per hour (201 km/h) west of Philadelphia.

On March 18, 2020, Amtrak temporarily suspended all Keystone Service trains due to declining demand because of the ongoing COVID-19 pandemic.

[46] On July 6, 2020, Amtrak restored one Keystone Service train in each direction running the full route between New York City and Harrisburg.

[50] From March to November 2021, midday Keystone Service trains were replaced with buses west of Lancaster to allow for track work.

The stop would be about halfway between Lancaster and Parkesburg, serving the local Plain community and allowing tourists to transfer to the Strasburg Rail Road.

A July 2004 plan was rejected by the Federal Railroad Administration over concerns that the curved track would preclude ADA-compliant boarding platforms.

[58] Before the signal, track, and catenary upgrades that were completed in October 2006, Keystone Service trains used GE Genesis diesel locomotives between Harrisburg and Philadelphia.

[3] Media related to Keystone Service at Wikimedia Commons For 150 mph (241 km/h) or more in the US, see High-speed rail in the United States