Virtually every city other than a few that are essentially islands or peninsulas that are fully built out like San Francisco and New York City. Some examples of cities with plenty of residential buildable land to expand into in the United States are Houston, Dallas, Austin, San Antonio, Tulsa, Atlanta, Charlotte, Orlando, Tampa (ex Saint Pete which is a peninsula), Jacksonville, Fort Meyers, San Diego, Los Angeles, Bakersfield, Sacramento, Las Vegas, Phoenix, Baltimore, Richmond, Greenville, Nashville, Knoxville, Chattanooga, and a myriad of other cities.
I already explained why prices go up when there is sufficient supply: hyper-fueled demand from essentially free money and new entrants like hedge funds looking for ways to invest the loads of cash they can borrow for nothing and money from their investors as well. In many cities, more than 30% of all home purchases were from investors.