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The Louisiana Purchase was the acquisition of the territory of Louisiana by the United States from the French First Republic in 1803. This consisted of most of the land in the Mississippi River's drainage basin west of the river. -
The Lewis and Clark Expedition, also known as the Corps of Discovery Expedition, was the United States expedition to cross the newly acquired western portion of the country after the Louisiana Purchase. -
The Adams–Onís Treaty of 1819, also known as the Transcontinental Treaty, the Spanish Cession, the Florida Purchase Treaty, or the Florida Treaty, was a treaty between the United States and Spain in 1819 that ceded Florida to the U.S. and defined the boundary between the U.S. and Mexico. -
The Indian Removal Act was signed into law on May 28, 1830, by United States President Andrew Jackson. The law, as described by Congress, provided "for an exchange of lands with the Native Americans residing in any of the states or territories, and for their removal west of the river Mississippi. -
The Trail of Tears was an ethnic cleansing and forced displacement of approximately 60,000 people of the "Five Civilized Tribes" between 1830 and 1850 by the United States government. -
The Battle of the Alamo was a pivotal event and military engagement in the Texas Revolution. Following a 13-day siege, Mexican troops under President General Antonio López de Santa Anna reclaimed the Alamo Mission near San Antonio de Béxar, killing most of the occupants. -
The Oregon Trail has attracted such interest because it is the central feature of one of the largest mass migrations of people in American history. Between 1840 and 1860, from 300,000 to 400,000 travelers used the 2,000-mile overland route to reach Willamette Valley, Puget Sound, Utah, and California destinations. -
Texas became the 28th state in the United States. Formerly part of Mexico, Texas had been an independent country since 1836. Since its independence, Texas had sought annexation by the U.S. However, the process took nearly 10 years due to political divisions over slavery. -
The Mexican–American War, also known in the United States as the Mexican War, was an invasion of Mexico by the United States Army from 1846 to 1848. It followed the 1845 American annexation of Texas, which Mexico still considered its territory because Mexico refused to recognize the Treaties of Velasco. -
The Mormons settled in the Salt Lake Valley, which at that time was used as a buffer zone between the Shoshones and the Utes, who were at war. Upon arriving in the Salt Lake Valley, the Mormons developed and cultivated the arid terrain to make it more suitable. -
The California Gold Rush was a gold rush that began on January 24, 1848, when gold was found by James W. Marshall at Sutter's Mill in Coloma, California. The news of gold brought approximately 300,000 people to California from the rest of the United States and abroad. -
In 1849, Californians sought statehood and, after heated debate in the U.S. Congress arising out of the slavery issue, California entered the Union as a free, nonslavery state by the Compromise of 1850. California became the 31st state on September 9, 1850 -
The American frontier, also known as the Old West, popularly known as the Wild West, encompasses the geography, history, folklore, and culture associated with the forward wave of American expansion -
The Gadsden Purchase is a 29,640-square-mile region of present-day southern Arizona and southwestern New Mexico that the United States acquired from Mexico by the Treaty of Mesilla, which took effect on June 8, 1854. -
Manifest destiny was a belief in the 19th-century United States that White American settlers were destined to expand across North America. It was an early expression of American imperialism in the United States of America.