The two-year exploration by Lewis and Clark was the first transcontinental expedition to the Pacific Coast by the United States; however, Lewis and Clark reached the Pacific 12 years after Sir Alexander Mackenzie had done so overland in Canada. When they left Fort Mandan in April 1805 they were accompanied by the 16-year-old Shoshone woman, Sacagawea, the wife of the French-Canadian fur trader, Toussaint Charbonneau. The Corps of Discovery made contact with many Native Americans in the Trans-Mississippi West and found them accustomed to dealing with European traders and already connected to global markets.