By the close of the 18th century, Ohio was also completely filled up by the settlements of the white men, while the natives, who had sold their birthright, slowly retreated before them into the present states of Illinois and Indiana. But yet again the same programme was gone through. The whites, to whom so much room had already been given, clamored for more; again their Government listened to their demands. The level lands, watered by sluggish streams, between the Ohio and the Wabash, were bought as those of Ohio had been, and received, as if in irony of the unlucky Indians who had taken refuge there, the name of Indiana. In a similar manner was formed the State of Illinois, the Sack, Fox, and other more northerly tribes ceding their territories as readily as their southern neighbors had done. Now and then some pioneer penetrated into the southern districts of Michigan, where, as we know, the French had long since established outposts, and in which were now situated Detroit and Mahimillimac, the two chief seats of the Canadian fur-trade. In 1803, the purchase by the Americans of five millions of acres between Lakes Michigan and Huron brought the emigrants from the States face to face with those from Canada. There were no more unoccupied districts to be bought in the neighborhood of the Great Lakes; and it will be in company with the scientific explorers of modern times that we shall renew our acquaintance with the border lands between the American Republic and Canada. Returning in the wake of emigration to the South, we find the cession of French territory to the Americans in 1763 resulting in the influx, into the districts between Georgia and the Mississippi, of a vast number of adventurers from the old states and the new. The general name of Louisiana, given by the first comers to the whole of the valley of the Mississippi, became restricted to the small state between the Father of Waters and the then Spanish Texas, while the new and important American settlements on the east of the great river were called Mississippi in its honor. A little later, the tract between the new state of Mississippi and Georgia was settled under the title of Alabama, and of all the eastern districts between the St. Lawrence and the sea there remained but Florida――still, in spite of a temporary change of ownership between 1763 and 1801, in the hands of the Spanish――to be acquired by the ambitious American Government. That its possession was eagerly coveted will be readily understood, and after a long series of negotiations, combined with the occasional use of force, it was annexed to the great republic in 1821. As a matter of course, the Mississippi was not long allowed to present any barrier either to emigration or exploration, and the taking possession of the districts on the east was but a preliminary step toward the acquisition of the vast tracts stretching away to the Pacific on the west.