Pennsylvania Railroad

The Clocker was originally a Pennsylvania Railroad express train service between New York and Broad Street Station in Philadelphia;^[1] the name was unofficial, and PRR timetables did not use it. Soon after New York Penn Station opened in 1910, the express trains began departing New York and Philadelphia on the hour through the day, giving rise to the Clocker name (which the railroad itself seems never to have used). Until the electrification of the Northeast Corridor in 1933, most Clockers were scheduled to both leave and arrive on each hour, but faster schedules after electrification eliminated the on the hour arrival.

Pennsylvania Railroad cut back on the schedule, and by the time Amtrak took over the nation's passenger rail service on May 1, 1971, the Clocker service no longer ran hourly.

Amtrak

At the launch of Amtrak, the railroad assigned each run an individual name (listed in the table below). Starting with the October 1981 timetable, Amtrak officially adopted the Clocker name for the service.^[2] The trains were unreserved, coach class only, and Amtrak targeted the Clocker service at commuters travelling to local stops bypassed by the high-speed Metroliner trains, the Regional trains, and other named long-distance trains.

During the 1990s, NJ Transit started contracting with Amtrak to accept their monthly passes on the Clocker trains. These two decisions drastically shifted the clientele on the trains. Monthly ticket holders from New Jersey preferred the Clocker trains over the NJ Transit trains because they were faster and more comfortable, meanwhile, Amtrak's passengers avoided the Clocker trains because they were slower and frequently crowded. Also, the monthlies meant that few passengers traveled to or from Philadelphia.

Until 2002, the 7:59 AM Clocker from Princeton Junction included a private club car known as Club 200 that members paid up to $1,200 per year to join (equivalent to $2,033 in 2023). This was the last private club car used in regular commuter service on the Northeast Corridor.^[3]

When the Acela Express was introduced in 1999, Amtrak launched what it called the Capstone Program, a short-lived plan to re-brand the NortheastDirect, Keystone Service and Empire Service trains as Acela Regional and the Clocker trains as Acela Commuter.^[4] Following mass rider confusion between this service and the high-speed Acela Express service, the name reverted to Clocker in 2003.^[5]

By the early 2000s, NJ Transit was paying $6 million per year to compensate Amtrak for monthly ticket holders riding Clocker trains,^[6] and was loaning Amtrak its new ALP-46 locomotives to haul the trains' Amfleet coaches.

On October 28, 2005, Amtrak discontinued the Clocker service altogether and sold the Northeast Corridor operating slots to NJ Transit which used them to partially replace the service with additional Northeast Corridor Line express trains between Trenton and New York City at times approximating the Clocker schedule.^[7]