Towards the end of the 1950's the PRR was looking for a new electric loco to be used in front of freight trains to replace the less suitable P5a in this role. A few years earlier, the Virginian had purchased the EL-C from GE, which performed well in the Blue Ridge Mountains to pull heavy coal trains. So the PRR ordered a development of the EL-C with similar optics and also an ignitron rectifier from GE. They were built like American diesel locomotives, i.e. with one cab, load-bearing frame and narrower hoods that were accessible via open running boards. The single diamond-shaped pantograph of the predecessor was replaced by two single-arm pantographs. Thanks to new developments in the field of electronics, the output could be increased from 3,300 to 4,400 hp. 

With a starting tractive effort of 96,0000 lbf and a dynamic brake, the locomotives are ideal for heavy freight trains on mountainous routes. The E44s were only used in exceptional cases to pull passenger trains, as they could only go 70 mph and had no boiler for train heating. The last six of the 66 engines were designated E44a because they had an output of 5,000 hp thanks to new diode rectifiers. The manufacturer converted another 22 E44s to the E44a status by 1970.

The reason why the remaining E44s were not converted was the collapse of the PRR, as a result of which all E44s and E44a first went to Penn Central and later to Conrail. At Conrail, the remaining Ignitron rectifiers were replaced with diode technology, with the output remaining unchanged. All engines were shut down in 1981 when Conrail stopped electric operations. They were later sold cheaply to Amtrak and NJ Transit, although NJ Transit found no use for them and gave them to Amtrak. There they spent the time until the mid-nineties in switching service for passenger traffic and were then scrapped.

NJ Transit had used the ALP-44 on the electrified routes since the late 1980s, which was based on the AEM-7, which in turn was derived from the Swedish Rc. In 1999, the first 24 three-phase locomotives were ordered from Adtranz, which were based on the German class 101 and were intended to replace the ALP-44. They were manufactured in the Kassel plant and have been delivered by Bombardier since 2001.

The machines weighed a few tons more than the class 101 and were only designed for 100 mph due to the possible speeds on the NJ Transit network. On the east coast of the USA there are three different AC systems that the locomotives had to be suitable for. As with the class 101, GTO thyristors were used to control the power, but here each axle was not controlled separately and one bogie each was combined to form a control group. This connects them with the TRAXX locomotives, which Bombardier now offers in Europe and which, compared to the 101, have simplified traction electronics. A total of 29 ALP-46s were procured by 2002.

Between 2009 and 2011, another 36 pieces of the successor called ALP-46A were procured to replace the last ALP-44s. These now used IGBT thyristors and had an hourly output of 5,600 instead of 5,300 kW. Although the NJ Transit network was still not designed for speeds higher than 100 mph, the ALP-46A was built for a maximum speed of 125 mph in the event of later route expansions. In 2011, the Canadian GO Transit considered the purchase of the ALP-46A as part of the planned electrification of some routes, which did not happen. Since the work is currently not scheduled to begin until 2023, there will be a renewed search for suitable locomotives in due course.

Several non-electrified commuter routes lie between New York City and several cities in New Jersey. However, since the crossing under the Hudson River can only be used by electric locomotives, passengers used to have to switch from diesel-powered trains to other trains. In order to ensure an uninterrupted journey, New Jersey Transit initially ordered 26 passenger locomotives with fully-fledged diesel and electric drives from Bombardier in Kassel in 2008, with options for a further 63. Because Canadian operator Exo, which operates commuter rail services around Montreal, had the same problem with the Mount Royal Tunnel, they joined NJ Transit and ordered 20 with an option for 10 more.

Bombardier based the ALP-45DP on the ALP-46, which was an all-electric locomotive and is closely related to the European TRAXX locomotives. The designation stands for “American Locomotive Passenger”, 4 axles, 5 megawatts, “Dual Power”. All the equipment had to be accommodated in a four-axle locomotive with a maximum axle load of 72,000 pounds anyway. Since the locomotives were only to be used in push-pull trains with control cars, a second driver's cab was not required.

Like the ALP-46, the drive technology for electric operation is based on that of the TRAXX 2E, which is used in Germany as class 186 and enables a top speed of 125 mph or 201 km/h. In the ALP-45DP, however, it only delivers 5 megawatts. In order to achieve an output of more than 3,000 kW in diesel operation, the choice fell on two light, fast-running twelve-cylinder engines from Caterpillar, each with its own generator. These are designed in such a way that if one motor fails, the locomotive can still be used with the other. The top speed is limited to 100 mph or 161 km/h in diesel mode.

The drive technology is designed in such a way that the change between the modes can even take place while driving and there is no interruption to the power supply of the train. However, the NJ Transit locomotives were manipulated in such a way that the change can only take place when stopping at a station in order to prevent them from gliding along without power during the 100 seconds required for this. Regardless of the current operating mode, up to 1,000 kW can be diverted to supply the passenger cars, which reduces the drive power available at the wheel to 2,039 kW in diesel mode.

At NJ Transit, the first delivery replaced the various passenger variants of the EMD GP40. After the first batch, 17 more were ordered in 2017. In 2020, another eight were ordered to replace Alstom's older PL42AC. At Exo, in 2019, the part of the route they traveled in electric mode was integrated into the new driverless metro. They are now only operated in diesel mode.

To replace the aging AEM-7 and unreliable HHP-8, Amtrak ordered a variant of the Vectron from Siemens. It is used as ACS-64, which means “Amtrak Cities Sprinter 6,400 hp”. It only delivers 5,000 kW permanently and 6,400 kW for short periods and is designed for the three different AC systems on the east coast. The locomotive body was designed to be significantly more stable and heavier in accordance with American crash standards. Amtrak procured 70 and SEPTA, which operates transit services in the Philadelphia area, received 15.