The United States grew very large. It took land from others. It also made deals with other lands. This changed how people lived. Some things were very unfair. Do you want to learn more?
The United States grew very large.
Long ago, the land grew by taking space. It took land from Mexico. It also bought land from Russia. 
This was hard for Native American groups. Many lost their homes. Some even died from new sicknesses.
Later, the U.S. grew in other ways. It took islands like Hawaii. It also worked with other lands for trade.
People still talk about these choices today. Some say it helped the world. Others say it was not fair.
American imperialism is when the United States uses power outside its borders.
In the 1800s, the U.S. grew by taking land. It won land from Mexico in a war. It also bought Alaska from Russia in 1867. 
This growth was very hard for Native Americans. Many groups lost their land through wars or broken treaties. Some died from new diseases like smallpox. In the 1830s, many were forced to move on the Trail of Tears.
Later, the U.S. changed how it grew. It began to control other places through trade and deals. It took control of islands like Hawaii. Presidents like Theodore Roosevelt helped lead this change. Some people said it was for trade. Others said it was to spread American ideas.
During the Cold War, the U.S. tried to stop communism. This led to the Vietnam War. This war cost many lives. Today, people still debate these actions. Some think they help the world. Others say they go against freedom.
American imperialism is when the United States uses power outside its own borders. This can happen in many different ways. Sometimes it means taking over new land through war or conquest. Other times, the U.S. uses trade, treaties, or money to influence other countries. It can even mean using cultural influence to change how people live. People have debated these actions for a long time. Some believe these actions help the world stay stable. Others argue they go against ideas like freedom and democracy.
In the 1800s, the U.S. grew by adding large amounts of land. 
This expansion caused great hardship for Native American communities. Many groups lost their land through wars or broken treaties. Some people died from diseases like smallpox that were brought from far away. In 1830, the Indian Removal Act led to the Trail of Tears. This forced 60,000 Native Americans to move west. Sadly, 16,700 people died during that journey. Later, the Dawes Act of 1887 changed how land was owned. This led to the loss of 100 million acres of land by 1934.
By the late 1800s, the way the U.S. grew began to change. 
In the 1900s, U.S. actions focused on different global goals.
American imperialism describes the exercise of power by the United States beyond its own borders. This concept involves how the nation interacts with other countries to gain influence or control. In the early years, this power often meant taking land through conquest or colonialism. Later, the methods changed to more indirect forms of control. The United States began using alliances, foreign aid, and economic influence through private companies. It also used gunboat diplomacy, which is using military force to pressure other nations. Other methods included signing treaties, supporting specific political groups, and attempting regime change.
In the 19th century, expansion was driven by the idea of manifest destiny. This was the belief that the United States was destined to expand across the North American continent. One major step was the 1803 Louisiana Purchase. This deal transferred 828,000 square miles of land from France to the United States. Later, the Mexican-American War from 1846 to 1848 resulted in the annexation of 525,000 square miles of Mexican territory. 
This period of expansion had devastating consequences for Native American communities. The U.S. military fought many wars against sovereign Native American groups. Many settlements were depopulated by diseases like smallpox, which were imported unwittingly. The Indian Removal Act of 1830 led to the Trail of Tears. During this event, 60,000 Native Americans were forced west of the Mississippi River. Sadly, 16,700 people died during this relocation. Later, the Dawes Act of 1887 replaced tribal land systems with private property. This change caused Native Americans to lose 100 million acres of land between 1887 and 1934.
Conflict also occurred in the Southwest and the Great Plains. In the 1860s, the Navajo faced a forced relocation known as the Long Walk. About 200 Navajo people died during this journey. In the Great Plains, the discovery of gold caused new settlers to flood into tribal lands. This led to the Colorado War and the Sand Creek Massacre, where up to 600 Cheyenne were killed. The discovery of gold in the Black Hills was very profitable. The Black Hill Mine produced $500 million in gold, which triggered the Great Sioux War. These events show how resource discovery often drove territorial conflict.
By the late 1800s, the focus of American power shifted toward "new imperialism." This era involved looking toward the Caribbean and the Pacific islands. The United States annexed Hawaii and became involved in the Spanish-American War. Leaders like Theodore Roosevelt were major figures during this time. Roosevelt believed in expansionism and used the Monroe Doctrine to influence the Western Hemisphere. Some people justified this by claiming a need to "civilize" others. Others, like Senator Albert Beveridge, argued that American factories produced more than citizens could consume. They believed the world's trade must belong to the United States. 
During the 20th century, foreign policy shifted toward the Cold War. The United States adopted the Truman Doctrine and the Reagan Doctrine. These policies aimed to "contain" the spread of communism and limit the Soviet Union. This era included the Vietnam War, which resulted in tremendous costs in lives for both Americans and Vietnamese. The United States also attempted regime changes in countries like Iran, Cuba, Panama, and Grenada. It also interfered in the elections of other nations.
Today, the legacy of this history remains visible in several ways. Some areas of the United States are still considered territories. These include Guam, Puerto Rico, the U.S. Virgin Islands, American Samoa, and the Northern Mariana Islands. Residents of these places are U.S. citizens. The debate over American power continues to be a central part of political discussion. Some see these interventions as necessary for global stability or economic interests. Others argue they contradict American values of democracy and independence. 
🖼️ Images & Media (44)
+ 32 more
More to explore
✨ What else?
Related topics you might enjoy
🔬 Go deeper
More advanced topics to explore
🪜 Step back
Simpler topics to build understanding
What is Nepedia?
A free, ad-free encyclopedia for children. Every article is written at five reading levels, so the same page works for a five-year-old and a fifteen-year-old — use the level switcher above to see this one change. No account needed to read.