Economic expansion in the late 19th century and early 20th century was driven by economic expansion and unique beliefs. In the past, the United States was an agricultural nation and its economy was based on agriculture. Since the United States' economy is based on agriculture, their expansion was necessary for the country's growth. However, over time, the slow transition from agriculture to big business changed the motivations for American expansion. However, in both eras, the United States was able to justify its expansion through national conviction. Before the 19th century, America had an economy based on agriculture and wanted to expand its nation for this purpose. The United States slowly grew after the American Revolution through warfare and land purchases. Thomas Jefferson signed the Louisiana Purchase in 1803, which doubled the size of the United States, encouraging greater land use and westward expansion. This expansion, however, caused problems that led to wars such as the Civil War. As new lands were acquired through these treaties, problems such as the expansion of slavery and relations with Native Americans arose. America grew through land treaties such as the Louisiana Purchase and the Gadsden Purchase, as well as wars like the Spanish-American War and the Mexican War. However, over time, land treaties and wars lessened and expansion beyond North America became another motive. America slowly but eventually transitioned from an agriculture-based economy to a more commercial and commercial economy. At the time, nations had their own spheres of influence, and within that sphere they tried to dominate trade. In the document A cartoon by Thomas Nast shows countries trying to establish their... middle of paper ......is and through natural selection the strongest survived. Josiah Strong states "the final racing competition, for which the Anglo-Saxons are trained..." and he also states in his last sentence "And can there be any doubt that the result of this racing competition will be survival of the fittest". This was linked to imperialism because stronger countries like Britain and France used this "burden" as an excuse to express control over weaker countries. American expansionism in the late 19th and early 20th centuries was similar due to its economic power and religious beliefs. Before the 19th century, the United States economy was agricultural, and in the early 20th century it transformed into a commercial economy. As the United States became a stronger nation, it began to expand its influence to other countries..