"Our manifest destiny is to expand the continent allocated by Providence for the free development of our millions who multiply every year." - John L. O' Sullivan, 1845. In 1820, the American population numbered 9,638,453 citizens and owned 1,749,462 square miles of land. Due to the population continuing to grow, America must find a way to expand more land for more people to live, thus creating the birth of the expansion of the Western world. From just nine million people, America has grown dramatically to 23 million citizens in thirty years. How she explores more and more lands, including new arrivals. In this essay I will show how America developed and grew thanks to this event, and how did it begin, what kind of events happened, how America is the America of 'Today. To begin with, the idea of ​​the expansion of the Western world was started by a group of people called "Mountain Men", by the people who live in the East. These people's mission was to track down the beaver. For what ? Beavers were very demanding in the 19th century. Their furs were used as clothing (or hats, blankets, etc.), which was “in fashion” at that time. The mountain men must be pushing west, since the beaver has disappeared in Europe and they have also disappeared in the east, due to their ever-increasing popular demand. Rocky Mountain beavers were their target. Undertaking this journey has its own pros and cons for the Mountain Men. Firstly, they traveled to earn money for themselves and their families, and they also tell stories about their journey, many of which were sold in books, making the idea of ​​the expansion of the more popular western world, inspiring families and people to settle down. the West for themselves. But during this journey, these men faced many trials, they required......middle of paper......2,000 men and many weapons. The United States also bombarded the city from the sea. They continued to advance toward Mexico City. After a long battle, Mexico surrendered. The Treaty of Guadalupe Hidalgo was signed between the United States and Mexico on February 2. Have the United States own California, Nevada, Arizona, New Mexico, Utah, Colorado, Wyoming and Texas, while agreeing to respect the Mexican citizens who still live in these States. All of these events were part of the expansion, from the beginning of Mountain Men to the Mexican-American War. Showing that America has grown and changed enormously in just under a decade. Showing the power and development of America. How they won many battles and conquered the land for themselves. To prove that they are superior, as if it is their destiny, but it seems that it is. Without these events, America would not be the way it is today.