Pressure from European-American settlers increased during the early nineteenth century, after invention of the cotton gin made cultivation of short-staple cotton profitable. This was readily cultivated in the upland areas of the South, and its development could feed an international demand for cotton in the 19th century. Migrants from the United States entered Mississippi mostly from the north and east, coming from the Upper South and coastal areas. Eventually they gained passage of the Indian Removal Act in 1830, which achieved federal forced removal of most of the indigenous peoples during the 1830s to areas west of the Mississippi River.