As we must be reminded, some parts of Suburbia (the outer fringe) still have rural characteristics and low costs that allow low-cost government. Some of the older suburbs are by contrast increasingly urban in character as infrastructure becomes expensive to maintain or even replace (like sewers at the end of their service lives and streets that require upgrades) and high-density housing (apartments) supplant low-density housing. Part of the Democratic trend may not be so much that 'classic' Suburbia that resembles the immediate post-WWII suburbs are going liberal as that the suburbs of the years just after WWII are themselves becoming old and often as decrepit as parts of the nearby cities.
Yup. Gary, Indiana is an excellent example of this. It's a "micro-city" in Indiana that also happens to be part of the Chicago Metro area and it's suffered horrendous urban decay over the past 50 years.
