For years past now, many Chicagoans have been bemoaning the increasing "Manhattanization" of Chicago, as more neighborhoods of single-family homes and two-family flats are rebuilt with large apartment buildings and condominium complexes containing 50 or more units.
However, increasing the city's density is the only way to reduce waste, create walkable neighborhoods, and provide support for quality retail and city services such as rapid transit. Most of all, the high density megacity is possibly the only way we can accomodate a swelling population in the coming era of permanent resource scarcity.
I recently found a great site, Walkable Cities, which reprinted an article by David Owen, that was originally published in The New Yorker, entitled "NYC is the Greenest City in America" (www.walkablestreets.com/manhattan.htm). Owen builds an elegant case for the high-density megacity as the only plausible solution to the energy squeeze and the massive destruction of farmland and natural habitats that have resulted from suburban sprawl.