How did major western rivers play a role in the discoveries made by Lewis and Clark and Pike?

Explanation:

On January 18, 1803, U.S. Pres. Thomas Jefferson sent a secret message to Congress asking for $2,500 to send an officer and a dozen soldiers to explore the Missouri River, make diplomatic contact with Indians, expand the American fur trade, and locate the Northwest Passage (the much-sought-after hypothetical northwestern water route to the Pacific Ocean). The proposed trip took on added significance on May 2, when the United States agreed to the Louisiana Purchase—Napoleon’s sale of 828,000 square miles (2,100,000 square km) of French territory for $27 million. Jefferson, who had already sponsored several attempts to explore the West, asked his personal secretary, Meriwether Lewis, to lead the expedition. Lewis was dispatched to Philadelphia for instruction in botany, celestial navigation, medicine, and zoology. He also purchased supplies and spent $20 on a Newfoundland dog, Seaman.

william marbury filed suit against secretary of state james madison because madison refused to deliver the justice of the peace commission former president john adams awarded marbury under the organic act of 1801.

it foreshadows the theme of the paragraph and hints the topic that will be discussed in the paragraph!