I was involved in a project where we could identify Transit deserts (https://en.wikipedia.org/wiki/Transit_desert https://en.wikipedia.org/wiki/Transit_desert).

I was involved in a project where we could identify Transit deserts (https://en.wikipedia.org/wiki/Transit_desert https://en.wikipedia.org/wiki/Transit_desert). Sadly the new administration cancelled this project. We were using GTFS data and US Census data to identify these. Quite interesting stuff. Perhaps the OP is interested in that as well.