Who commissioned Meriwether Lewis and William Clark to form an expedition to explore the Louisiana Territory?

Answer 1

First of all, it was Meriwhether Lewis who was assigned to explore the West. Clark would offer to join up with the Discovery Corp weeks after Meriwether Lewis started his journey in Pittsburgh (yes, that's right, Pittsburgh, not St. Louis. Check out the related link to the Lewis and Clark Journals for that fact)

Jefferson's instruction to Lewis were:

"Beginning at the mouth of the Missouri, you will take observations of latitude and longitude at all remarkable points on the river, & especially at the mouths of rivers, at rapids, at islands & other places & objects distinguished by such natural marks & characters of a durable kind, as that they may with certainty be recognized hereafter....The variations of the compass too, in different places should be noticed."

(considering the Native Americans) "...You will therefore endeavor to make yourself acquainted, as far as diligent pursuit of your journey shall admit with the names of the nations & their numbers, the extent & limits of their possessions; their relations with other tribes or nations; their language, traditions, monuments, their ordinary occupations in agriculture, fishing, hunting, war, arts & the implements for these, their food, clothing, & domestic accommodations, the diseases prevalent among them, & the remedies they use, moral and physical circumstance which distinguish them from the tribes they know, particularities in their laws, customs & dispositions, and articles of commerce they may need or furnish & to what extent."

"Other objects worthy of notice will be the soil & face of the country, it's growth & vegetable productions, especially those not of the US; the animals of the country generally & especially those not known in the US; the remains & accounts of any which may be deemed rare or extinct; the mineral productions of every kind, but more particularly metals, limestone, pit coal & saltpetre, salines & mineral waters, noting the temperature of the last & such circumstances as may indicate their character; volcanic appearances; climate as characterized by the thermometer, by the proportion of rainy, cloudy & clear days, by lightening, hail, snow, ice, by the access & recess of frost, by the winds, prevailing at different seasons & the dates at which particular plants put forth or lose their flower or leaf, times of appearance of particular birds, reptiles or insects."

Answer 2

Thomas Jefferson had dreamed of exploring the West for at least 20 years before he even became President. In 1783 he had even asked William Clark's brother, George, to take on the challenge. The Louisiana Purchase would later alter the character of the planned expedition from an exploration of French territory to a first glimpse of lands that, in the view of many contemporaries, were essential to maintaining the agrarian, republican character of the nation.

The Louisiana Territory had been a land purchase transaction by the United States of America of 828,800 square miles of the French territory "Louisiane" in 1803. The U.S. paid 60 million francs ($11,250,000) plus cancellation of debts worth 18 million francs ($3,750,000), a total cost of $15,000,000 for the Louisiana Territory.

After finally purchasing the Louisiana Territory, Jefferson had requested $2500 from Congress to pay for the costs of the trip. However that money was used to provide for medicine, gifts for the Native Americans and camp equipment. Jefferson as well as those in the American Philosophical Society would provide minor donations of books, maps, and scientific equipment. To pay for supplies obtained from trading posts along the way Lewis and Clark used a government issued IOU. They also did a lot of bartering, especially with Native Americans.