Lesson 12 · 20 min
This lesson covers the wars of the 1900s and why the United States entered them, the Great Depression, the Cold War, the civil rights movement, September 11, 2001, and famous American innovations.
World War I began in Europe in 1914. On one side were the Allied Powers, including England, France, Italy, and Russia. On the other side were the Central Powers: Germany, Austria-Hungary, the Ottoman Empire, and Bulgaria.
At first the United States stayed out of the war. But German submarines attacked ships carrying American civilians, people who are not soldiers, and many Americans died. In 1917, President Woodrow Wilson asked Congress to declare war, and the United States joined the Allies. The fighting ended on November 11, 1918.
Women had worked for the right to vote since the 1800s, and many women helped the country during the war. In 1920, soon after the war, the 19th Amendment gave women the right to vote across the country.
In October 1929, the stock market crashed, which means the prices of company shares fell very fast. This Great Crash started the Great Depression, the longest economic recession in modern history. A recession is a time when business slows down and many people lose their jobs, and during the Depression millions of Americans lost their jobs, homes, and savings.
Franklin D. Roosevelt became president in 1933. His programs, called the New Deal, created jobs and helped people in need. He was elected four times, more than any other president, and he led the country through the Great Depression and most of World War II until his death in April 1945.
World War II began in Europe in 1939. The Axis Powers were Germany, Italy, and Japan. The Allied Powers included England, France, and Russia, which was then part of the Soviet Union, and later many other countries.
On December 7, 1941, Japan made a surprise attack on U.S. Navy ships at Pearl Harbor in Hawaii. The United States then entered the war. It fought Japan, Germany, and Italy and supported the Allies until the war ended in 1945.
General Dwight D. Eisenhower led the Allied forces in Europe in World War II, including the D-Day landings in France in June 1944. In 1953 he became the 34th president, and the Korean War ended during his first year. In 1956 he signed the Federal-Aid Highway Act, which created the Interstate Highway System.
After World War II, the United States and the Soviet Union, also called the USSR, became the two strongest countries in the world. Russia was the largest part of the Soviet Union. The two countries were rivals, or competitors, in a long struggle called the Cold War, from the late 1940s to 1991.
The Soviet Union had a communist government. Under communism, the government controls the economy and people have few political freedoms. The United States worried that communism would spread to more countries. Both countries also built many nuclear weapons, so Americans feared a nuclear war.
To stop the spread of communism, the United States fought in the Korean War (1950 to 1953) to defend South Korea against communist North Korea. For the same reason, it fought in the Vietnam War to help South Vietnam against communist North Vietnam, and American combat troops left Vietnam in 1973. The Soviet Union broke apart in 1991, and the Cold War ended.
After slavery ended, many Black Americans still faced racial discrimination, which means unfair treatment because of race. In many Southern states, laws kept Black and white people apart in schools, buses, and restaurants. This is called segregation.
The civil rights movement fought to end racial discrimination, mostly in the 1950s and 1960s. In 1955, Rosa Parks refused to give up her bus seat to a white man in Montgomery, Alabama, and Black residents then refused to ride the city buses for more than a year. Peaceful protests, marches, and court cases like this changed many unfair laws.
Dr. Martin Luther King, Jr. was a pastor and the best-known leader of the movement. He used peaceful methods and worked for equality for all Americans. In his famous 'I Have a Dream' speech in Washington, D.C., in 1963, he shared his hope that his children would be judged by their character, not by the color of their skin.
The movement helped pass the Civil Rights Act of 1964 and the Voting Rights Act of 1965. Dr. King was killed in 1968. Today, Martin Luther King, Jr. Day, a federal holiday in January, honors his life and work.
In 1990, the army of Iraq invaded its small neighbor, Kuwait. In early 1991, the United States led a group of countries in the Persian Gulf War to force the Iraqi military out of Kuwait. The war was short, and Kuwait was freed.
On September 11, 2001, terrorists attacked the United States. Terrorists are people who use violence against ordinary people to create fear for political goals. They took control of four passenger planes and crashed two into the World Trade Center towers in New York City and one into the Pentagon, the headquarters of the U.S. military, in Arlington, Virginia. The fourth plane was headed toward Washington, D.C., but crashed in a field in Pennsylvania after passengers fought back, and almost 3,000 people died that day.
After these attacks, the United States began the Global War on Terror. It fought the War in Afghanistan (2001 to 2021) and the War in Iraq (2003 to 2011).
Americans are also known for innovations, which are new inventions or new ways of doing things. Thomas Edison developed a practical light bulb in 1879, the Wright brothers flew the first successful airplane in 1903, and Henry Ford's moving assembly line made automobiles cheap enough for many families. American cities built the first skyscrapers, American engineers created the integrated circuit (a tiny computer chip) around 1958, and in 1969 American astronauts were the first people to land on the moon.
The 1900s means the years 1900 to 1999. In that century the United States fought in both World Wars, in Korea and in Vietnam. The Persian Gulf War in 1991 was near the end of the century.
World War I started in Europe in 1914, and at first the United States stayed out of it. German submarines attacked ships and killed Americans at sea. In 1917 the United States joined the war on the side of the Allies.
Women across the whole country won the right to vote in 1920 with the 19th Amendment. This came soon after World War I. Memory hook: the 19th Amendment came in 1920, so think of 19 and 20 side by side.
The Great Depression was a very long and very bad time for the economy, starting in 1929. Many banks and businesses closed, and millions of people lost their jobs. At its worst, about one in four workers had no job.
The Great Depression started when prices on the stock market fell very fast in October 1929. Many people lost their savings almost overnight. This event is called the Great Crash.
Franklin D. Roosevelt was president from 1933 to 1945. He led the country through the Great Depression and most of World War II. He is the only president elected four times.
On December 7, 1941, Japan made a surprise attack on the U.S. Navy base at Pearl Harbor, Hawaii. The next day, the United States declared war on Japan. Soon it was fighting the Axis Powers together with the Allies.
Dwight Eisenhower was a top general in World War II and led the D-Day landings in France in 1944. Later he was the 34th president, from 1953 to 1961. He signed the law that built the Interstate highway system.
The Cold War was a long struggle between the United States and the Soviet Union, from the late 1940s until 1991. The two countries did not fight each other directly in a big war. The Soviet Union broke apart in 1991, and Russia was its largest part.
During the Cold War, the United States worried that communism would spread to more countries. Both the United States and the Soviet Union built many nuclear weapons. People feared a nuclear war that could destroy whole cities.
In 1950, communist North Korea invaded South Korea. The United States and other countries sent troops to help the South and stop communism from spreading. The fighting lasted from 1950 to 1953.
Vietnam was divided into a communist North and a non-communist South. The United States helped the South to stop communism from spreading in Asia. American combat troops fought there in the 1960s and early 1970s.
The civil rights movement worked to end unfair treatment of people because of their race, especially Black Americans. Its biggest years were the 1950s and 1960s. It led to new laws such as the Civil Rights Act of 1964.
Martin Luther King, Jr. was a pastor and a leader of the civil rights movement. He used peaceful protest to fight for equal rights. In his famous "I Have a Dream" speech in 1963, he hoped people would be judged by their character, not their skin color.
In August 1990, Iraq invaded its small neighbor, Kuwait. The United States led a group of many countries to push the Iraqi army out. The main fighting took place in early 1991 and was short.
On September 11, 2001, terrorists took control of four passenger planes and attacked the United States. Two planes hit the World Trade Center in New York City, and one hit the Pentagon. The fourth crashed in a field in Pennsylvania, and nearly 3,000 people died that day.
After the September 11 attacks, the United States began a long fight against terrorist groups around the world. U.S. forces went into Afghanistan in 2001 and into Iraq in 2003. The last U.S. troops left Afghanistan in 2021.
An innovation is a new idea or invention that changes how people live. The Wright brothers flew the first powered airplane in 1903. In 1969, American astronauts were the first people to walk on the moon.
The 1900s are the years 1900 to 1999. U.S. wars from that time include World War I, World War II, the Korean War, the Vietnam War, and the (Persian) Gulf War. You only need to name one.
Woodrow Wilson was President during World War I. The war lasted from 1914 to 1918, and the United States joined in 1917. Memory hook: World War I and Woodrow Wilson both start with W.
Franklin Roosevelt (often called FDR) was President during the Great Depression and most of World War II. He was elected four times, more than any other President. His face is on the dime.
In World War II, the United States fought against Japan, Germany, and Italy. The United States entered the war after Japan attacked Pearl Harbor, Hawaii, on December 7, 1941. Say all three countries.
Dwight Eisenhower was a top U.S. general in World War II. He commanded the Allied forces in Europe, including the D-Day landings in 1944. He later became the 34th President.
The Cold War was a long period of tension between the United States and the Soviet Union, from the late 1940s to 1991. The main concern of the United States was the spread of Communism. It was called "cold" because the two countries never fought each other directly.
The civil rights movement worked to end racial discrimination and segregation, especially in the 1950s and 1960s. It led to new laws such as the Civil Rights Act of 1964. Martin Luther King, Jr. was one of its best-known leaders.
Martin Luther King, Jr. was a leader of the civil rights movement who worked for equal rights for all Americans using peaceful methods. He gave the famous "I Have a Dream" speech in 1963. A federal holiday honors him on the third Monday in January.
On September 11, 2001, terrorists took control of four airplanes and attacked the United States. The planes hit the World Trade Center in New York and the Pentagon near Washington, D.C., and one crashed in Pennsylvania. Nearly 3,000 people died.
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Lesson text is original study material based on the USCIS 2025 Civics Test Study Guide topics. Editorial status: draft, pending expert review.