Port Colborne has some home construction, but is building subdivisions at a much slower pace than Welland. However there are many subdivisions proposed in the pipeline. The largest one under construction is in the North end here that will fill in the land near West Side Rd/Hwy 58. The residents of the idyllic 1960s subdivision Hawthorne Heights are going to be pissed to have houses crammed in by their backyards

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In SW Port, an extension of Westwood Estates is happening here, South of Stanley St and East of Cement Rd:
The 72 unit condo midrise on West St has injected life into the city's oldest retail strip.
Find local businesses, view maps and get driving directions in Google Maps.
maps.app.goo.gl
Most buildings on West St. are from the mid-late 19th to early 20th century. The cruise ships have brought extra tourists in, but I'm not sure how long they spend in Port Colborne as most will do side excursions to Niagara Falls or wineries. Port Colborne benefits from the influx of summer cottagers along Lake Erie from Western NY and the GTA.
Port Colborne population growth. A lot of old timers have died off and new families moved in to replace them as new houses have been built.
2004: 19,245
2014: 18,840
2024:
21,830
Welland has subdivisions and infill happening all across the city, not just the North end. Just view a satellite shot and scroll across the city to see the dirt for new subdivisions.
The biggest one is Empire Homes development in the South end (Dain City) on/near the grounds of the former John Deere plant, with the former Welland canal/recreational waterway on the West and current Welland Canal (1970s bypass) on the East. IIRC, around 2,000 housing units will be built when all phases are complete.
My cousin told me they are bussing kids from here into Port Colborne until they build a new school in this subdivision. A lot of young families have bought in this area, primarily from the GTA it seems.
For Northern Light, here's the Longo's plaza site plan for the North end of Welland on Niagara St at Quaker Rd. It's being developed by plaza REIT.
When the nearby apartments, townhouses and retail is filled this will be one of the busiest locations in the city. They tore down the old Big Lebowski-esque

Bowl-o-Rama for this.
Welland population growth
2004: 51,480
2014: 52,711
2024:
63,874
Niagara region population growth
2004: 437,364
2014: 450,656
2024:
539,180
Since 2021, the fastest growing municipalities in Niagara by raw numbers:
Niagara Falls +17,378
St. Catharines +16,155
Welland +8,124
Fort Erie +4,044
Thorold + 3,497
On realtor.ca I sorted by housing units listed as built since 2015 (by newest listings for sale) to give you an idea of the stuff from schlock to decent that's being built in
Niagara region. If the realtor doesn't enter the built date the homes won't show up in search that's why there's so few showing.