The problem is ultimately how property taxes and local ordinances work in the US. It’s cheaper to buy and develop undeveloped land than to tear down and redevelop existing property. If the tax laws and ordinances were written to make it more profitable to redevelop existing property, it would go a long way to change this trend. And it would make sense for communities to do this, the larger the land area developed for a municipality, the greater the expense for maintaining streets, sidewalks, drainage, police, fire, schools, etc. So how could this be done? One example would be for property tax to be, in part, based on historic boundaries, so the farther you go from the city center the higher the taxes. Or, you could grandfather property taxes, so, you could build a brand new building or house on the property of an old house and charge the taxes based on the old house.