Why did the U. S. expand west in the 1840s and what territories did America gain as a result of Manifest Destiny?

Following a trail blazed by Lewis and Clark, most of these people had left their homes in the East in search of economic opportunity. Like Thomas Jefferson, many of these pioneers associated westward migration, land ownership and farming with freedom. In Europe, large numbers of factory workers formed a dependent and seemingly permanent working class; by contrast, in the United States, the western frontier offered the possibility of independence and upward mobility for all. In 1843, one thousand pioneers took to the Oregon Trail as part of the “Great Emigration.”  Then in 1848 The California Gold Rush was sparked. By the discovery of gold nuggets in the Sacramento Valley, and was arguably one of the most significant events to shape American history during the first half of the 19th century. As news spread of the discovery, thousands of prospective gold miners traveled by sea or over land to San Francisco and the surrounding area; by the end of 1849, the non-native population of the California territory was some 100,000 (compared with the pre-1848 figure of less than 1,000). A total of $2 billion worth of precious metal was extracted from the area during the Gold Rush, which peaked in 1852.   .

Explanation:

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Following a trail blazed by Lewis and Clark, most of these people had left their homes in the East in search of economic opportunity and they gained Arizona, California, western Colorado, Nevada, New Mexico, Texas, and Utah.

Explanation:

these acts divided the south into five military districts.