Steam Powered Opinions notes the decline of St. Louis, which appears to me as best described economically the Southern-most outpost of the Rust Belt. Its fate mirrors that of the more extreme case of Detroit. Like many central cities, its downfall was greatly furthered by urban planning approved, interstate highway assisted suburbanization. Timothy Lee's blog has explored the issue at length in multiple posts from his perspective as a libertarian, one who appears to be liberal leaning, or at least, free of some of the nasty "hate the world" cynicism that sometimes accompanies that label.
A comment to the post linked suggests that white flight from the central city was also a factor. While the comment doesn't reach this conclusion, most of the narratives of white flight point to school desegregation in the wake of Brown v. Board of Education and subsequent cases as a factor that was an important as the interstate highway system in the migration away from central cities. (Equally important, in my view, was the U.S. Supreme Court case follow up to Brown that held that desegregation efforts did not have to extend beyond racially neutrally drawn school district lines.)
One of the fascinating aspects of the fight over land use generally is the extent to which local politics in the United States are decoupled from national ones. You will find die hard Democrats and Republicans alike at both ends of the land use debates played out mostly in local politics, even when, as in this case, national policies concerning civil rights and transportation had a major impact.
You will find proponents of strong land use regulations in liberal strongholds like my Washington Park neighborhood in Denver (which has been home to much of the legislative leadership of the Democratic party in Colorado at one point or another), where the instinct is a preservationist/historic one, although also anti-density, and yet you will also find proponents of strong land use regulations in affluent, conservative suburbs like Cherry Hills Village and Greenwood Village to the Southeast of Denver.
Meanwhile, you will also find proponents of weaker land use regulations like myself, among proponents of infill development, who see urban density as mostly a virtue, for environmental and economic development reasons among other motivations, while weak land use regulations also find favor among conservative suburban developers of large lot tract housing.
The decoherence of local political ideology compared to national political ideology is probably one reason why it leaves open room for constructive engagement across traditional political identity boundaries. It is a place where “liberaltarian” common ground (what a god awful word!) is possible, as are other unlikely alliances.
Timothy B. Lee, who is confident enough in his own judgment to take libertarian heroes like Austrian school economist Ludwig von Mises with a grain of salt, and to recognize that issues that don't impact him personally are still important, is certainly an easier voice to hear libertarian rooted ideas from than most.