Western Expansion, Manifest Destiny, and the Mexican-American War

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What is the significance of the Mexican Cession?

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The signing of the Treaty of Guadalupe Hidalgo on February 2, 1848, ceded a large portion of Mexican territory over to the United States. Mexico lost the large states of Alta California and Santa Fe de Nuevo Mexico. Essentially, Mexico ceded about half of its land to the United States.

There are many significant factors to consider that resulted from this event. First off, the United States grew greatly in size. Overnight, the United States became 500,000 square miles larger. This opened up the country to more westward expansion. Great numbers of settlers headed into the former the Mexican territories seeking new fortunes. Gold was discovered in California in 1848, leading to the Gold Rush. Homesteaders also headed west in order to settle these lands. This accounted for the largest migration of Americans ever at the time. Furthermore, natural resources such as minerals and lumber from the west greatly improved the country's economy.

The Mexican cession also had great significance in regards to the issue of slavery. Slavery had been illegal in Mexico since Mexico's independence from Spain. Now the question as to whether slavery would exist in these new American territories drew a bitter divide. The Compromise of 1850 served to preserve the balance between free states and slave states and delayed the Civil War by a decade.

With territory stretching from coast to coast, railroad companies began the ambitious project of building the transcontinental railroad. They soon found that the topography of Arizona did not allow for easy railroad construction. Consequently, the United States purchased a strip of land from Mexico in 1853 in what was known as the Gadsden Purchase.

For Mexico, the loss of all this land was a huge embarrassment. The citizenry was justifiably outraged. The war and the cession of territory destroyed the country's economy. A civil war known as the Reform War followed, as liberal and conservative forces vied for power in their weakened nation. It would be about a century before Mexico would recover economically and politically from this event.

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The Mexican Cession was important to our history. After the war with Mexico ended, the Treaty of Guadalupe Hidalgo was signed. As a result, this treaty established our Mexican-United States border at Texas at the Rio Grande River. We also got California, Utah, and Nevada from Mexico. In addition, we got parts of Colorado, Utah, and New Mexico from Mexico. Getting all of these areas fulfilled our goal of Manifest Destiny, which was expanding our control over lands from the Atlantic Ocean to the Pacific Ocean. With the exception of a very small amount of land in southern Arizona and New Mexico, we now controlled the land in what makes up the lower 48 states.

Gaining this land also intensified the debate over the spread of slavery. Both the North and the South viewed these new lands as possible free states and slave states. There would be many discussions regarding these lands. In the Compromise of 1850, California would be allowed to join the United States as a free state. People would decide if there would be slavery in the Utah and New Mexico territories. Thus, while the Mexican Cession presented many opportunities, it also increased the tension over the spread of slavery.

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The Mexican Cession is the huge tract of land that the US got from Mexico as a result of the Mexican American War.  It is significant for two reasons.

First, it greatly enlarged and enriched the United States.  The gold in California and the silver in Nevada were just two examples of the wealth of this area.  Second, by obtaining the Mexican Cession, the US moved closer to the Civil War.  The US had to decide whether the territories organized from the new land would be slave or free.  This led to more conflict between the North and South and helped to bring about the Civil War.

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