The New York Times reports such battles are raging in Washington, D.C., Austin, Texas, and elsewhere and describes one such fight brewing in a New York City borough: "Last month in Brooklyn, when a state development agency unveiled a long-awaited environmental impact study of the proposed Atlantic Yards project, critics complained that their worst fears had been realized. The developer, Forest City Ratner Companies, wants to plop more than a dozen buildings as high as 62 stories onto 22 acres near downtown Brooklyn, where a mix of vacant lots, low-rise apartments, abandoned buildings, and condominiums now sit. The developer says that the massive residential, office, and arena complex would bring housing and jobs to a borough in need of both."
All I can say to the two sides is, guys you'd better patch it up. There's one and only one alternative to higher-density development, and it's an alternative neither side seems inclined to embrace: downsizing the U.S. population. Most liberals I know support unfettered immigration. The more people emigrate to the U.S., the more houses they need to live in, neighborhoods they need to shop in, etc.
This split, while not yet major, enters its incipient phase just as progressives are poised to make their first major political gains in a decade (in congressional elections this November.) What awful timing! The last thing progressives need is yet another point of disunity. They do disunity quite well enough (unlike conservatives, who march in militialike lock step.)