The present-day PATCO Speedline follows the route of several historical mainline railroad lines, some dating back to the 19th century.

Early in the 20th century, the idea of a fixed Delaware River crossing connecting Camden and Philadelphia gained traction, and in 1919, the states of Pennsylvania and New Jersey formed the Delaware River Bridge Joint Commission to build a bridge between the two cities.

In Philadelphia, the line joined the 1932-opened Broad-Ridge Spur just west of Franklin Square and shared its 8th Street/Market Street station.

[17] To facilitate the construction of extensions in Southern New Jersey, the states expanded the powers of the Delaware River Joint Commission (which owned the Benjamin Franklin Bridge and the New Jersey portion of the Bridge Line), rechristening it as the Delaware River Port Authority (DRPA) in 1951.

A later study by Louis T. Klauder & Associates recommended using the Bridge Line instead to reach Philadelphia and suggested building Route B first, as it had the highest potential ridership.

[21] An infill park and ride station, Woodcrest, was added on February 1, 1980, along with the PATCO II railcars.

The proposed Glassboro–Camden Line would require riders to transfer to the Speedline at the Walter Rand Transportation Center for trips to Philadelphia.

[31] The line began operating limited service on March 28, 2020, due to the COVID-19 pandemic, with trains bypassing 12–13th & Locust, City Hall, Westmont, and Ashland stations.

[35] The PATCO II cars were delivered in 1980 (in parallel with the opening of the Woodcrest Park and ride facility) and consisted of married pairs numbered 251-296.

[35] As built, the PATCO cars used camshaft resistance type motor controllers common to DC powered rapid transit vehicles up through the 1980s.

The married pair cars shared a single motor control unit and automatic operation box.

Many PATCO Car design features also appeared in the M1/M3 class of MU railcars for the Long Island Rail Road which provides for a similar riding experience.

PATCO announced plans for the complete refurbishment of the entire fleet with work expected to begin in 2009.

[37] PATCO began to ship the railcars with their trucks removed and replaced with highway tires for the road trip to the Alstom facility in Hornell, New York, in March 2011.

[38] The refurbishment consisted of a completely new interior with more modern colors, wheelchair access and more reliable HVAC systems.

The General Electric DC motors, Pioneer III trucks and gearboxes were not replaced, but rebuilt by Alstom as well.

[39] As of March 24, 2019[update], the refurbishment work has been completed with a total of 120 of the previous 121 cars accepted back into service.

The remaining single unit #116 was excluded from the rebuilding program due to having been damaged beyond repair by an arson fire in 1997 and subsequently used as a source of spare parts.

Automatic station stops are handled by track mounted transponders and can be overridden by the operator for non-stopping trains.

[35] The system suffers from problems handling slippery track conditions and human operators are required to take control in any sort of precipitation.

In its first several decades, PATCO actively managed consist length based on ridership levels as opposed to running trains in fixed sets, with single car trains making the occasional appearance overnight prior to the elimination of single cars as part of the rebuild.

[35] Due to recent capital improvements, weekend and mid-day headways have grown, prompting PATCO to run 4 or 6 car trains during most off peak times, albeit less frequently than the 2-car trains and social distancing requirements of the COVID 19 pandemic further increased the use of 6-car trainsets during off-peak times.

[35] The entire PATCO system is run from Center Tower, centrally located above a substation near the Broadway station in Camden.

In New Jersey power is distributed via wayside AC transmission lines in the 26.4 kV range and a series of 7 substations, located approximately every 2 miles (3.2 km).

[35] PATCO was one of the first transit systems to employ automated fare collection and tickets with magnetically stored data.

There are also no unlimited ride pass options, however a reduced fare Freedom Card is available for senior citizens and disabled riders.

At the start of service in 1969, PATCO used a system of plastic tickets with an oxide layer on the entire back side for the magnetic encoding of data.

Used tickets with no remaining rides were retained by the faregates, re-encoded at a PATCO facility and returned to use in the vending machine.

Tickets were vulnerable to damage from magnetic sources and the equipment to read and code the farecards began to suffer from reliability problems with little replacement part availability.

More importantly, the fare system could not accept payment cards and the reliance on change machines created an extra step for those needing to pay with paper currency.