I don’t see how you can class either of those areas as blue or red. Considering most of the people who live there are students or from immigrant backgrounds (last 15 years/ lack of interest in football/ hard to know)
Fallowfield and Longsight are not totally transient. There are solid Mancs of all colours in settled communities, semis and big houses there. It might be a bit more evenly split now that City has left the area but when I was kid, the diverse neighbourhoods off the 41, 42, 43 bus routes were very Blue - you felt a powerful local connection to the club whether or not you got to games.
It was Alex Williams who came into schools, it was City who laid things on for local kids and crucially it was Maine Rd, Platt Lane and City fans that you could see. And there was pride that City played out of Moss Side representing streets like Claremont Rd, Great Western Street, Lloyd Street where the kids grew up watching cars and enjoying the matchday buzz.
Though I’m going to be controversial now and say that I’ve always thought the ground straddled Fallowfield, Rusholme and Moss Side rather than sitting in Moss Side proper.
‘Manchester’ in matchgoing terms is a sphere of influence of at least 50 miles of where we play, and the matchgoing support is a lucky snapshot of it, perhaps a bit older than it might have been because you need more disposable income these days.
And obviously Stockport and Tameside are massively Blue. But the streets nearest grounds - whether its Maine Rd, the Etihad, even Old Trafford - are part of the soul of a club imo. They are the mixed working class communities who see and feel the local and community side of clubs day in day out and hear the roar of the ground from their homes - and they produce players.