A vast area of plains to the east of the Rocky Mountains in North America, extending from the valleys of the Mackenzie River in Canada to southern Texas.
大平原（北美洲落基山脉以东的大平原地区，从加拿大的马更些河谷延伸至美国得克萨斯州南部）
Definition of Great Plains in US English:
Great Plains
proper nounˌɡrāt ˈplānz
A vast area of plains to the east of the Rocky Mountains in North America, extending from the valleys of the Mackenzie River in Canada to southern Texas.