As others have said, the dividing line is more about income than whatever politics tend to align with income in a given area. Here&#x27;s an example from Boston with the Red Line <a href="http:&#x2F;&#x2F;boston.curbed.com&#x2F;archives&#x2F;2014&#x2F;02&#x2F;the-red-line-stops-in-arlington-and-lexington.php" rel="nofollow">http:&#x2F;&#x2F;boston.curbed.com&#x2F;archives&#x2F;2014&#x2F;02&#x2F;the-red-line-stops...</a><p>(Arlington and Lexington, even at that time, were relatively upper income but would also have been fairly liberal--at least by national standards.)