Densest U.S. cities aren’t the ones you think

Advocates of energy-saving urban density usually laud the towering buildings and subways of Manhattan, as contrasted with the car-heavy suburban sprawl of, say, Los Angeles. But the most dense city in the U.S., measured by people per square mile, is … Los Angeles. In fact, despite its reputation for sprawl, the West contains 10 of the country’s 15 most densely populated urban areas, among them San Francisco, Las Vegas, and San Jose. At work is not a miracle of urban planning but physical limitations: a pervasive lack of water, large mountain ranges, and huge tracts of federally owned land. “Infill” development squeezes residences into every scrap of available land. Among the wealthy, planned (and often gated) communities pack houses relatively close together while preserving views and suburban amenities. But the real secret to density in many large Western cities is poverty: Often two, three, even four poor immigrant families cram into one residence, filling garages, attics, and sheds. A reminder that growth should be not only smart, but compassionate.