Medium-size metros in Texas and the Mountain Time Zone are faring the best.

The study identified 8,000 Airbnb listings that advertised so frequently that they were likely illegally converted into hotel rooms. This situation has caused rents to rise in the city, the study contends.

Y Combinator plans to solicit proposals for research into construction methods, power sources, driverless cars, and even examine concepts of zoning and property rights.