 There, at and beyond the western edge of the Appalachian plateau, the terrain became less hilly.In addition, navigable waterways like the Kanawha River and the Ohio River led to the Mississippi River, and thence to the Gulf of Mexico.After the Louisiana Purchase from France in 1803, an acquisition by the United States of most of the land along the Mississippi and Missouri Rivers, about 530,000,000 acres (828,000 sq mi or 2,100,000 km²) of territory, the portions of this area along navigable waterways were settled by Americans moving west and immigrants, mostly English and other northern Europeans, gradually squeezing out the Native Americans in the process.