Four hundred fifty-six days after leaving Saint Louis, Meriwether Lewis wrote that he had accomplished one of the great objects on which his mind had long been fixed. On August 12, 1805, Lewis, George Drouillard, Hugh McNeal, and John Shields crossed the Continental Divide here ahead of the main expedition, leaving the headwaters of the Missouri and entering the upper Columbia River Basin. At 7,373 feet (2,247 meters), Lemhi Pass is the highest elevation on the westward route of Lewis and Clark. Hoping to find a practical land portage between the Missouri and Columbia Rivers, they called this place Portage Hill, but after five weeks of difficult travel through the Rocky Mountains they learned it was not the Northwest Passage they sought. In 1805 this was the boundary between two nations, and after the 1803 Louisiana Purchase, British and U.S. interests raced to occupy the Pacific Northwest and control its trade routes and commerce while both countries failed to fully acknowledge the sovereignty of resident Indian nations.