Westward expansion and Manifest Destiny were touchy and controversial subjects in this time. Many people believed that the nation had the right to expand and acquire new land. But, a lot of people thought otherwise. They believed that this theory was just an excuse to gain more land and wealth, not an attempt to better the Western world. The Second Great Awakening and the religious zeal that followed were also more incentive to move west. The followers of this movement believed that they were obligated by God to move west and spread their religious teachings. They intended these teachings for "heathen" Native Americans, as well as Mexicans that lived in the newly acquired territories of California, New Mexico, and Texas.
Another reason to go West was the Gold Rush of 1949. Many people travel thousands of miles just to go to California based on the chance that they might find gold. These people were known as '49ers. Because of this event, San Francisco grew from a small settlement of about 200 people to a city of 30 some thousand.
The Lewis and Clark Expedition was also a major occurrence that was part of Westward Expansion. This expedition was commissioned by Thomas Jefferson and was led by Meriwether Lewis and William Clark. Thomas Jefferson's alleged purpose for this expedition was to find "the most direct and practicable water communication across the continent, for...commerce".