On my flight home from California last week, I took the photo above. It's not the greatest photo, but I captured the image to illustrate the edge of suburban sprawl in some place or other, I'm not sure where.
Reviewing it later, one of the things that struck me is that the development protruding onto the landscape in the photo is actually relatively high-density, as single-family residential development goes. Those are small lots, and my very wild guess is that we could be looking at 15-20 homes per acre, enough to pass the density prerequisite of LEED for Neighborhood Development and maybe even earn a density point or two.
Getting the right city density - generally expressed in the US as people per square mile or homes per acre - to support sustainable and pleasant living is one of the trickiest problems we face as we address the future of our communities. The typically low densities of suburban sprawl built in the last half of the 20th century, despite their popularity at the time with a considerable share of the market, have been shown by a voluminous body of research to produce unsustainable rates of driving, carbon emissions, pollution. stormwater runoff, and adverse health impacts.