Throughout the first half of the 1800s or 19th century there were many factors influencing United States expansion. From the Louisiana Purchase in 1803 to the Gadsden Purchase in 1853 the United States had tripled in size since its original thirteen colonies and only paid forty-five million dollars in doing so. The idea of Manifest Destiny spread quickly throughout the country and soon thousands were moving westward in search of a new way of life. The idea of Manifest Destiny was for the U.S. to occupy the entire continent. The only problem was that the land it was expanding on to didn’t belong to the U.S.

             One such factor that influenced the expansion of the U.S. was the occupation of nearby territories by foreign countries. The largest territory and first one to be bought by the U.S. was the Louisiana Purchase of 1803. In order for the United States to expand successfully into the west they needed control of the Mississippi River, which at the time was owned by France. The port at New Orleans was extremely important to the navigation of the Mississippi and provided a good market for trade. While this purchase was very successful, others did not go as well. Prior to the Mexican Cession of 1848 the United States and Mexico were having boundary disputes over where the Texas boarder existed. President Polk reacted by sending troops into Mexico to protect the Texas boundary lines. A year and a half later Mexico surrendered and Texas was granted the Rio Grande border line in the Treaty of Guadalupe. Because of the different nations or countries that owned land on the continent, the U.S. was forced to purchase or fight for the land it wanted. This caused the newly acquired territories to have a more diverse group of people, which affected the social development of the nation as a whole.

             Another huge factor that played a role in expansion was that of available resources. As the people began to move westward they would settle in areas with vast amounts of natural resources such as lakes or streams, where they could gather food.