Urban sprawl is the way a city spreads into undeveloped land around it, often without planning permission.

城市扩张是指未经计划审批，城市向未开发的地区扩张。

They were enthusiasts and obsessives who took advantage of the unfettered access to undeveloped land afforded by a young country pressing its frontier westward.

他们狂热而迫切，年轻的国家正在向西部扩充领土，所以他们可以利用这种优势，自由使用未开发的土地。