This paper, based on the author’s new book The Urban Fix: Resilient Cities in the War against Climate Change, Heat Islands and Overpopulation (2019), culminates over three decades of researching, teaching, and writing on American sprawl. One of the country’s biggest and most familiar problems, it could be described as a conspiracy of good intentions: short-sighted desires to live in nature; traffic safety engineers’ preference for wide thoroughfares; fire marshals’ desire to turn around hook-and-ladder trucks at the end of every cul-de-sac, etc. Over half of American homes are single-family dwellings – 69 million out of a total of 132 million. The fatal flaw is that these positive intentions quickly led to very high energy/carbon/ecological footprints per suburbanite – a challenge that is difficult because of extensive, indelible infrastructure. Densifying arterial strips, inserting transit, redeveloping a walkable, bikeable, mixed-use, and human-scaled urbanity is as urgent as it is essential in the nation’s effort to combat climate change.