- This article is about the use of Acela as a brand. For the high-speed train service, see Acela Express.
Acela is a brand applied by Amtrak to its high-speed trains along the Northeast Corridor in the Northeast U.S., called Acela Express. Prior to 2003, the Acela Regional name was applied to most local trains on the corridor, now simply called Regional to avoid confusion. The Acela Commuter name was proposed but never used for the Clockers, and Acela Regional was planned for all trains on the Empire Corridor and Keystone Corridor in addition to the Northeast Corridor. In fiscal year 2006, a total of 2,668,174 passengers rode Acela, an 8.8% year-over-year increase. 
|Amtrak Northeast Corridor|
|The Acela brand|
(including Virginia and NHV-SPG)
|Former services: Clocker - Metroliner|
|Other Amtrak trains on the NEC:|
Cardinal - Carolinian - Crescent
Keystone - Palmetto - Pennsylvanian
Silver Meteor - Silver Star - Vermonter
|Commuter services on the NEC:|
MBTA - SLE - MNRR - NJT
SEPTA R7 - SEPTA R2 - MARC
On March 9, 1999, Amtrak unveiled its design for its new high-speed service, and announced that most services in the Northeast would be branded Acela. The name was a portmanteau of "excellence" and "acceleration", pronounced "ah-cel-la" [ə'sɛlə] (though a great many riders and staff call it "ack-cel-la" [ək'sɛlə], in keeping with the name's derivation). At that time, there were three classes of trains on the Northeast Corridor (and its extension south to Newport News, Virginia) — the hourly Philadelphia-New York Clockers, the express Metroliners, and the umbrella term NortheastDirect, applied to all other local trains on the corridor (in addition to unique names assigned to each departure). Empire Service trains used the Empire Corridor from New York City to Niagara Falls, and Keystone Service ran along the Keystone Corridor from Philadelphia to Harrisburg. Other named trains also used the corridors, branching off or continuing beyond their termini.
As announced, the original plan was to rebrand all services but those continuing beyond the termini as Acela. The Metroliners would be replaced with Acela Express. All NortheastDirect, Empire Service and Keystone Service trains would become Acela Regional. Finally, the Clockers would be Acela Commuter.
In reality, the Acela Regional name was first applied to NortheastDirect trains 130-133 on January 31, 2000. Those trains, 130 and 131 running weekdays only and 132 and 133 running every day, were the first electrified trains to run on the full Northeast Corridor. As more trains were electrified, they too were rebranded. Regular Acela Express service began December 11, 2000; at the time there were still part-diesel NortheastDirect trains. On March 17, 2003 the Acela name was dropped from the Acela Regional, with the trains simply being called Regional. Technical difficulties have led to a joke about Acela standing for "Amtrak Customers Extremely Late Again" trains. The Acela Commuter service never appeared. It simply remained known as the Clocker service up until October 28, 2005, when it was discontinued and New Jersey Transit introduced four new express trains between Trenton, NJ and New York City to make up for the lost service.
- Amtrak's former Acela website on the Internet Archive (active April 19, 1999 to September 23, 2001, after which it was redirected to Amtrak's main website)
- Event announcing Amtrak's Acela service
- Amtrak: News Release - March 9, 1999: Amtrak Rolls Out 'Acela' Service, High-speed Trains for Northeast
- Bob Johnston, Amtrak opens Boston electrification, Trains April 2000
- Ron Newman, Acela Regional starts Jan 31, 2000, misc.transport.rail.americas January 27, 2000
- Bob Johnston, Acela Express begins; NEC schedules revamped, Trains January 2001
- Rail Travel News - News Posting March 23, 2003