One of the largest and most wealthy countries in the world, the United States of America, has gone through many changes in its long history. From winning its independence from Great Britain to present day, America has changed dramatically and continues to change. A term first coined in the 1840s, "Manifest Destiny" helped push America into the next century and make the country part of what it is today. The ideas behind Manifest Destiny played an important role in the development of the United States by allowing the territorial expansion of the 1800s. Without the expansion of the era, America would not have most of the western part of the country it does now.
Manifest Destiny, before becoming nationally known, started very meagerly. The term "Manifest Destiny" was first used by Congressman Robert Winthrop before being made popular by John L. O"Sullivan in 1845 (Manifest Destiny). O"Sullivan first used the term, "Manifest Destiny" in an article he wrote for the Democratic Review in the July-August edition of 1845. O"Sullivan wrote to other nations who had, "the avowed object of thwarting our policy and hampering our power, limiting our greatness and checking the fulfillment of our manifest destiny to overspread the Continent allotted by Providence for the free development of our yearly multiplying millions" (Adams 332). He was actually talking about the annexation of Texas but the term was stolen from him and used by expansionists of the time to justify other annexations (Adams 332). .
Many causes fueling America's need to expand and acquire new lands existed. One of the reasons was Americans were experiencing "a large birthrate increase due to immigration. And because agriculture provided the primary economic structure, large families to work the farms were considered an asset" (Manifest Destiny: An Introduction). The population in 1800 was more than five-million and by the mid-century grew to more than twenty-three million (Manifest Destiny).