Urban growth boundaries (UGBs) help control urban sprawl and promote sustainable development. A new method was developed to define UGBs in rapidly growing cities by considering both urban connections and ecological conservation. By analyzing how cities interact and using a special computer model, researchers found that UGBs based on these factors can lead to more efficient urban development. In a case study in China, it was shown that UGBs that consider urban connections can help cities grow in a more organized and practical way.