on which river did the exploration of the louisiana purchase begin
Missouri River the Missouri River
title: Louisiana Purchase text: to explore and map the new territory. All three started from the Mississippi River. The Lewis and Clark Expedition (1804) traveled up the Missouri River; the Red River Expedition (1806) explored the Red River basin; the Pike Expedition (1806) also started up the Missouri, but turned south to explore the Arkansas River watershed. The maps and journals of the explorers helped to define the boundaries during the negotiations leading to the Adams–Onís Treaty, which set the western boundary as follows: north up the Sabine River from the Gulf of Mexico to its intersection with the 32nd parallel, due north to title: Louisiana Purchase text: ill-defined British possession—Rupert's Land of British North America, now part of Canada. The Purchase originally extended just beyond the 50th parallel. However, the territory north of the 49th parallel (including the Milk River and Poplar River watersheds) was ceded to the UK in exchange for parts of the Red River Basin south of 49th parallel in the Anglo-American Convention of 1818. The eastern boundary of the Louisiana purchase was the Mississippi River, from its source to the 31st parallel, though the source of the Mississippi was, at the time, unknown. The eastern boundary below the 31st parallel was unclear. The title: Louisiana Purchase Historic State Park text: Mississippi River, doubling its size. President Thomas Jefferson commissioned the Lewis and Clark Expedition, which traveled west along the Missouri and associated rivers, eventually reaching the Pacific Coast, from 1804 to 1806. President James Monroe ordered a survey of the territory in 1815, in order to permit the orderly award of land in the territory to military veterans of the War of 1812. Prospect K. Robbins and Joseph C. Brown were commissioned to identify a starting point for the survey work in what is now eastern Arkansas. The team led by Robbins traveled north from the mouth of the Arkansas title: Jefferson River text: United States acquired the Missouri River watershed through the Louisiana Purchase of 1803, and President Thomas Jefferson sent Meriwether Lewis and William Clark with a company of men to explore up the Missouri in the hopes of finding a navigable water route to the Pacific, with a low portage connecting one watershed with the other. The Expedition departed from Saint Louis, Missouri in the spring of 1804, ascended the Missouri River that summer, then wintered over with the Hidatsa Indians in North Dakota, where they met Toussaint Charbonneau and his Shoshone wife Sacagawea. Lewis and Clark hired Charbonneau to join title: History of St. Louis before 1762 text: it connected to the Pacific Ocean. On this mission, explorer Louis Joliet and Jesuit priest Jacques Marquette arrived at the Mississippi River in June 1673 and traveled past the confluence of the Missouri and Mississippi to the mouth of the Arkansas River. At this point Joliet returned north after determining the river would not reach the Pacific and fearing attack by Spanish settlers. Nine years later, French explorer La Salle led an expedition south from the Illinois river to the mouth of the Mississippi and claimed the entire valley for France. La Salle named the Mississippi river basin Louisiana after