Title: Louisiana
Content:  The first European explorers to visit Louisiana came in 1528 when a Spanish expedition led by Pánfilo de Narváez located the mouth of the Mississippi River. In 1542, Hernando de Soto's expedition skirted to the north and west of the state (encountering Caddo and Tunica groups) and then followed the Mississippi River down to the Gulf of Mexico in 1543. Spanish interest in Louisiana faded away for a century and a half. In the late 17th century, French and French Canadian expeditions, which included sovereign, religious and commercial aims, established a foothold on the Mississippi River and Gulf Coast. With its first settlements, France laid claim to a 
Title: Jefferson River
Content:  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 the expedition, in part because Sacagawea's people were native to the Missouri headwaters. The Lewis and Clark Expedition arrived at the Missouri Headwaters on 
Title: Old Baldy (Lynch, Nebraska)
Content:  For many years before the 1803 Louisiana Purchase, Thomas Jefferson had contemplated seeking a water route from the United States to the Pacific Ocean. With the acquisition of the Louisiana Territory from France, this could be done legally. Jefferson, now President of the United States, accordingly dispatched the Lewis and Clark Expedition up the Missouri River. The party was charged with following the main stem of the river to its headwaters and then finding rivers running westward from the Rocky Mountains to the Pacific. They were also directed to establish peaceable relations with the indigenous peoples of the region; to note mineral and other resources; to map the major physiographic features; and to describe and 
Title: Constitution of Louisiana
Content:  The beginning of statehood for Louisiana began with the Louisiana purchase in 1803. In 1804, the land the United States purchased from France was divided in two territories: 1) the Louisiana Territory (upper territory) and 2) the area below the 33rd parallel (current Louisiana-Arkansas state line), the Orleans Territory each as an organized incorporated territory of the United States. The Territory of Orleans formed the bulk of what today is the State of Louisiana. From the beginning there were border disputes. In 1795, the Treaty of Friendship, Limits, and Navigation Between Spain and the United States, known as Pinckney's Treaty, had set the 
Title: Louisiana Purchase
Content:  as far as the Perdido River, and Spain claimed that the border of its Florida Colony remained the Mississippi River. The Adams–Onís Treaty with Spain resolved the issue upon ratification in 1821. Today, the 31st parallel is the northern boundary of the western half of the Florida Panhandle, and the Perdido is the western boundary of Florida. Because the western boundary was contested at the time of the purchase, President Jefferson immediately began to organize three missions 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 
Title: Louisiana Purchase Exposition gold dollar
Content:  Much of the area near the Mississippi River was explored by French explorers in the 17th and 18th centuries. In 1682, René-Robert Cavelier, Sieur de La Salle, claimed the entire area drained by the river for France, naming it Louisiana for Louis XIV. Although most French territory in the Western Hemisphere was lost in the French and Indian War (1756–1763), the Mississippi basin did not pass to the victors in that war (primarily the British) as it had been secretly transferred to Spain by the 1762 Treaty of Fontainebleau. Napoleon came to power in 1799. Dreaming of a renewed French empire, he secured the return of the Louisiana territory from Spain via the Third Treaty of San Ildefonso the following year, and through other 
Title: Louisiana
Content:  Louisiana Territory, purchased for less than three cents an acre, doubled the size of the United States overnight, without a war or the loss of a single American life, and set a precedent for the purchase of territory. It opened the way for the eventual expansion of the United States across the continent to the Pacific Ocean. Shortly after the United States took possession, the area was divided into two territories along the 33rd parallel north on March 26, 1804, thereby organizing the Territory of Orleans to the south and the District of Louisiana (subsequently formed as the Louisiana Territory) to the north.
Title: Louisiana Purchase
Content:  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 the Red River, up the Red River to the 100th meridian, north to the Arkansas River, up the Arkansas River to its headwaters, due north to the 42nd parallel and due west to its previous boundary.
Title: History of Louisiana
Content:  The first European explorers to visit Louisiana came in 1528 when a Spanish expedition led by Panfilo de Narváez located the mouth of the Mississippi River. In 1542, Hernando de Soto's expedition skirted to the north and west of the state (encountering Caddo and Tunica groups) and then followed the Mississippi River down to the Gulf of Mexico in 1543. The expedition encountered hostile tribes all along river. Natives followed the boats in large canoes, shooting arrows at the soldiers for days on end as they drifted through their territory. The Spanish, whose crossbows had long ceased working, had no effective offensive weapons on the water and were forced to rely on their remaining armor and sleeping mats to block the arrows. About 11 Spaniards were killed along this stretch and many more wounded. Neither of the explorations made any claims to the territory for Spain.
Title: Louisiana Purchase Historic State Park
Content:  On April 30, 1803, negotiators for the United States and the First French Empire, signed the Louisiana Purchase agreement, by which the United States acquired 830000 sqmi of land west of the 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 

Question: on which river did the exploration of the louisiana purchase begin?
Answer: Missouri River.
the Missouri River.