Urban growth boundary

Urban growth boundaries are areas that separate how much an urban area can be developed or built upon. Basically, it's like a wall that's designed to keep cities from becoming too big. For example, a city might decide that it doesn't want to build any further outward because it wants to maintain a certain population size or certain amount of open space, so it would draw a boundary line and not let any more construction or development happen past that boundary. It helps keep cities in balance and makes sure they don't expand too far and get too big.