In the United States, imperialism exists because of a desire to demonstrate and extend the scope of American power overseas. The motives for imperialism are primarily the same for nations around the world. Imperialism happens when countries seek to expand their scope of influence and assert power and control on certain nations.
Imperialism occurs sometimes without the use of military forces, such as through political diplomacy. However, militaries also enforce and carry out acts of imperialism. In the U.S., imperialism emerged primarily during the 19th century. Prior to the late 1800s, the U.S. existed as an isolationist nation, taking measures to stay out of international affairs. The isolationist policy enforced by early American presidents, including George Washington, ended with the involvement of the U.S. in World War I. Several motivating factors led the U.S. to change course in pursuit of imperialism. Economic incentive to expand its market internationally and bring in additional revenue was a primary contributing factor. The U.S., like other nations, experienced a growth in technology that greatly improved the production of goods and services. Following the Great Depression of the 1920s, the U.S. saw a crucial and immediate need to fix a damaged economy, and resorted to imperialist policies and tactics to bring that change.