Here's a map by Jim Smiley that aims to visually represent gentrification in Philly by tracking the changes in how many building permits are pulled in any given area. It's an interesting method, but its results are a little strange.
The map shows areas with more than a 30% increase in building permits in red. While it's true that building permits are one good way to track gentrification, they're not always the most reliable indicators. This map, for example, would seem to suggest that Old City, Fairhill, Wister, West Powelton, Spruce Hill, Woodland Terrace, Mill Creek, and Dunlap are Philly's fastest gentrifying neighborhoods. It seems unlikely that Old City, which has been solidly gentrified for quite some time now, is experiencing another surge of gentrification.
The creator himself has reservations about using building permits as indicators of gentrification, especially when considering changes year to year: the map can sometimes indicate a decline in building permits, when really what's happening is that the area experienced a surge of building permits the year before.
· Gentrifying Philly: This map shows neighborhoods undergoing change [Technical.ly Philly]
· Gentrifying Philly [Code For Philly]