"If you live in a city - and every year, more and more Americans do - you've seen firsthand how gentrification has transformed our surroundings, altering the way cities look, feel, cost, and even smell. Over the last few years, journalists, policymakers, critics, and historians have all tried to explain just what it is that happens when new money and new residents flow into established neighborhoods, yet we've had very little access to the human side...