The name derives from the fact that it is situated at the north end of Park Avenue and is literally an "extension" of the artery.

Montreal started from a small fortified city by the Saint Lawrence River; and expanded north towards the Laurentian Mountains.

In the 2000s, more people starting moving to Park Extension from areas like the Plateau and Mile End as the housing is similar but much cheaper to rent and to buy.

All of this in turn, along with the new Université de Montréal campus between Beaumont and Van Horne Avenues, has caused gentrification and "renoviction" issues to affect the area gradually after about 2008 with various protests occurring in and after 2018.

During the "red scare" of the 1950s, according to an article in "On and Off the Record" in the Montreal Gazette dated April 24, 1956,[3] page 4: "The Park Extension district is currently a hot-bed of Communist activity; much or all of which is known to anti-communist authorities and groups, who are keeping it under surveillance."

The surrounding neighbourhoods are Villeray and Little Italy to the east, Mile End and Outremont to the south, the Town of Mont-Royal to the west and Ahuntsic-Cartierville to the north.

In addition, a short section of Park Avenue runs north from the western end of Liege St. just east of the CPR railway tracks.

The province wide Quebec Ball Hockey Association has three Parc-Extension area teams: the Hellenic Republic of Parc-Ex, Park X Streets, and A.A. Hellas.

The documentary, Cricket & Parc Ex: A Love Story (2016), by director Garry Beitel and producer Barry Lazar (reFrame Films), profiled the more recently arrived immigrant South Asian communities which have moved into Park Extension and how their love for the game of cricket brings them together.

Harris Newman (guitar) and Bruce Cawdron (percussion) recorded a song called "The Pulse of Parc Ex" on their 2006 album, Triple Burner.

The space between the station building and the railway line, where the original platforms were located, was occupied by a Provigo Le Marché supermarket[4] and its vehicular access.

A fence runs along the western border of Park Extension, on the opposite side of L'Acadie Boulevard in the Town of Mount Royal.

While the stated purpose of the fence is to prevent children from running into the busy thoroughfare, some have contended that it was built to keep residents of the working-class Park Extension neighbourhood out of TMR.

[6] The area covered by the residences in the Town of Mount Royal from L'Acadie in the east to Rockland in the west and between Lockhart in the south to Cremazie in the north was once a 9-hole golf course.

This fence originally had several gates built into it, which then became a subject of controversy when they were locked one year at Halloween, preventing children from Park Extension from trick-or-treating in TMR.