of Fort Vancouver, on the Columbia River. Fort Okanogan was later owned by the North West Company, and then the Hudson's Bay Company, both of which were British-owned. Both Native American and white trappers conducted fur transactions at the trading post, which was staffed by representatives of the fur trading company. During one season, Ross traded 1,500 beaver pelts. In 1814, Ross became the first known white explorer to explore the valleys and high passes of the North Cascades, but he was less interested in exploration than discovering a route that would easily connect the fur trading posts of interior Washington with Puget Sound to the west. Ross was accompanied by three Indians, one of whom was a guide who led the party to a high pass in the North Cascades. Ross and the guide may have traveled as far west as the Skagit River, but failed to get to Puget Sound. Fur trading slowed considerably as demand for furs decreased in the 1840s, but a few residents continued to augment their income by trapping for furs in the area until 1968, when the park was established, rendering the activity illegal. Aside from isolated trappers, the North Cascades saw no further explorations until the 1850s. In 1853, US Army Captain George B. McClellan led a party that explored the area for potential locations for the construction of a railroad through the region. McClellan determined the mountains were too numerous and precipitous, and that any railway would have to be constructed well to the south. American and British disputes in the region centered on the fur trade, and the Treaty of 1818 allowed for joint administration of Oregon Country, as it was referred to in the United Statesthe British Empire referred to the region as the Columbia District. The treaty set the international border at the 49th parallel, but this was disputed west of the Rocky Mountains, since the rival fur trading outfits had their own ideas about where the border should be. The Oregon boundary dispute between Britain and the United States eventually led to the Oregon Treaty of 1846, and the 49th parallel forms both the current international border as well as the northern limit of the current park. During the late 1850s, members of the US North West Boundary Commission explored the border region, attempting to identify which mountains, rivers and lakes belonged to which country. One party