THE EARLY EXPLORATION OF
In the year 1800 more than half the area that is now included in the United States was virtually unknown. In 1806 John Cary, the famous London cartographer, produced a "New Map of North America" (Fig. 1)1, a large portion of which is almost devoid of geographical features or names, thus showing that a vast area in the west of the present United States was still unexplored. This map was compiled from "the latest authorities", and nothing was marked on the map unless Cary possessed reliable information concerning its existence. Other mapmakers had been content to draw on their imaginations when making maps of North America, but Cary did not attempt to fill up the blank spaces of his map with imaginary features. Cary's map reflects the stage which the exploration of America had reached at the beginning of the nineteenth century.
THE DISCOVERY OF THE PACIFIC COAST .2 The outline of the Pacific coast was accurately indicated by Cary. The exploration of this coast had begun in the early years of the Spanish occupation of Mexico. In 1513 Balboa discovered the existence of the Southern or Pacific Ocean, and Cortés subsequently despatched several expeditions to explore the western coast of America. In 1533 one of these squadrons discovered lower California, which was at first believed to be an island. Cortés' last maritime expedition, led by Francisco de Ulloa in 1539, reached the head of the Gulf of California, doubled the southern____________________