Interesting comments on my neighborhood (only been here 7 years, so not much first hand that I can tell you). I live in that separated part south of the crosstown.
Despite what the map shows, I don’t believe your walk across the Bloomington Avenue bridge took you out of the city. It is a road maintained by the city. Both sides are clearly marked with a Minneapolis street sign. I was told that the bridge was built when the crosstown went in so city vehicles could reach our little area without having to drive through Richfield. I think the bridge may not be considered part of the Diamond Lake neighborhhood, but part of the city?
I also think there is an error in the map that you reference. The streets along 14th Ave from 60th are 60th, 61st, 62nd (south of crosstown), 62nd (north of crosstown) and 62nd (bordering Richfield.) I can say I live on 15th Avenue between 62nd street and 62nd street, just across the crosstown Highway from 62nd street! Here is a link to a map that shows the correct (I believe) naming:
Awesome project, I look forward to reading more.