Speaking as an Atlantan, you've nailed it. People living OTP (outside the perimeter of I-285) are largely conservative, whereas those ITP are much more liberal.

You wouldn't imagine that such a finely delineated categorical segmentation would occur, but it's very visible. Take, for instance, the fighting between Fulton County and the metro/MSA: last year's SPLOST vote [1], the Braves Stadium move [2], etc. all serve to exemplify how polar these two populations are.

Those in the city want regional tax money to improve transportation in and around the city, those outside the city want to be left alone (yet still be able to commute to the city); Atlantans bemoan urban sprawl, suburbanites loathe city spending. It's interesting to watch nothing get done.

[1] http://southernspaces.org/sites/southernspaces.org/files/ima...

[2] http://www.ajc.com/news/sports/baseball/braves-plan-to-build...