What physical feature once served as a natural boundary to western expansion? the Great Plains the Mississippi River the Appalachian Mountains the Great Lakes

The Appalachian Mountains once served as a formidable barrier to westward expansion in the early days of the United States. These rugged, rolling peaks created a natural division between the British colonies on the east coast and the vast territories that lay to the west, making travel and settlement significantly challenging. However, as pioneers sought new opportunities, the mountains became less of an obstacle thanks to the development of trails and roads, like the Wilderness Road. This shift allowed settlers to traverse the Appalachians and ultimately fueled westward migration, transforming the landscape of America forever.