- The Kellogg-Briand Pact, an international treaty renouncing war as an instrument of national policy, is signed by 65 nations.
- The first talking movie, "The Jazz Singer," is released.
- Amelia Earhart becomes the first woman to fly across the Atlantic Ocean.
- The St. Valentine's Day Massacre, in which seven mobsters are killed in Chicago, takes place.
1929
- The stock market crashes, sparking the Great Depression, a worldwide economic crisis.
- The Empire State Building is completed.
- The first Academy Awards ceremony is held.
1930
- Mahatma Gandhi leads the Salt March, a nonviolent protest against British rule in India.
- The Dust Bowl, a severe drought that affected the U.S. Southern Plains during the 1930s, begins.
- Adolf Hitler becomes the Chancellor of Germany.
- The first FIFA World Cup is held in Uruguay.
1931
- Japan invades Manchuria, beginning the Second Sino-Japanese War.
- The Hoover Dam, a hydroelectric dam in the United States, is completed.
- The Empire of Japan invades Manchuria, initiating World War II in the Pacific.
- The Nazis come to power in Germany.
- The United States repeals Prohibition.
1932
- Amelia Earhart becomes the first woman to fly solo across the Atlantic Ocean.
- Franklin D. Roosevelt is elected President of the United States.
- The Summer Olympics are held in Los Angeles.
1933
- Adolf Hitler becomes Chancellor of Germany.
- The Great Depression reaches its peak in the United States.
- Franklin D. Roosevelt takes office and begins implementing the New Deal, a series of programs designed to help the country recover from the Great Depression.
1934
- Congress passes the Social Security Act, providing a social safety net for the elderly, unemployed, and disabled.
- The Dust Bowl reaches its peak.
- The Nuremberg Laws, a series of laws that discriminated against Jews in Nazi Germany, are passed.
1935
- The United States and the Soviet Union establish diplomatic relations.
- Italy invades Ethiopia, beginning the Second Italo-Ethiopian War.
- The Nuremberg Laws are passed in Nazi Germany, stripping Jews of their citizenship and civil rights.
1936
- The Spanish Civil War begins.
- The Berlin Olympics are held in Nazi Germany.
- Jesse Owens, an African-American track and field athlete, wins four gold medals at the Olympics.
1937
- Japan invades China, beginning the Second Sino-Japanese War.
- The Hindenburg disaster, in which a German airship catches fire and crashes, killing 36 people, takes place.
- Franklin D. Roosevelt is elected to a third term as President of the United States.
1938
- Austria is annexed by Germany.
- The Munich Agreement, a pact between Germany, Italy, France, and Great Britain that allowed Germany to annex the Sudetenland region of Czechoslovakia, is signed.
- Kristallnacht, a night of violence against Jews in Nazi Germany, takes place.
1939
- Germany invades Poland, beginning World War II.
- Great Britain and France declare war on Germany.
- The Soviet Union invades Finland, beginning the Winter War.
1940
- Germany invades Denmark, Norway, Belgium, the Netherlands, and France.
- The Battle of Britain, an air battle between Germany and Great Britain, begins.
- The United States passes the Lend-Lease Act, providing military aid to Great Britain and other Allied countries.
- Charlie Chaplin's film "The Great Dictator," a satire of Adolf Hitler, is released.
1941
- Germany invades the Soviet Union.
- The United States enters World War II after the Japanese attack on Pearl Harbor.
- The Battle of Midway, a naval battle between the United States and Japan, takes place.
- The Allies invade North Africa.
1942
- The Battle of Stalingrad, the bloodiest battle in history, begins.
- The Allies invade Italy.
- The Manhattan Project, a secret research and development project that produced the atomic bomb, is established in the United States.
1943
- The Battle of Stalingrad ends in a Soviet victory.
- The Allies invade Sicily.
- The Italian government surrenders to the Allies.
- The Manhattan Project produces the first atomic bomb.
1944
- D-Day, the invasion of Normandy by the Western Allies, takes place.
- The Allies liberate Paris from German occupation.
- The Battle of the Bulge, the last major German offensive of World War II, takes place.
- The atomic bomb is dropped on Hiroshima and Nagasaki, Japan, forcing the Japanese to surrender and ending World War II.
1945
- The United Nations is established.
- The Nuremberg Trials, a military tribunal that tried Nazi war criminals, begin.
- The Cold War, a state of tension between the United States and the Soviet Union, begins.
- Winston Churchill delivers his "Iron Curtain" speech, warning of Soviet expansionism.
1946
- The Philippines becomes independent from the United States.
- The Cold War escalates as the United States and the Soviet Union compete for influence in Eastern Europe.
- J.R.R. Tolkien's novel "The Lord of the Rings" is published.
1947
- India becomes independent from Great Britain.
- The Truman Doctrine, a U.S. policy of containment of Soviet expansionism, is announced.
- The Marshall Plan, a U.S. program to provide economic aid to Western Europe, is launched.
1948
- The State of Israel is established.
- The first Berlin Airlift, a U.S.-led operation to supply food and other necessities to West Berlin, which was blockaded by the Soviet Union, begins.
- The United Nations adopts the Universal Declaration of Human Rights.
1949
- The North Atlantic Treaty Organization (NATO) is established.
- The Chinese Civil War ends with the victory of the Communists under Mao Zedong.
- The Soviet Union detonates its first atomic bomb.
- George Orwell's novel "Nineteen Eighty-Four" is published.