World history: the USA from boom to superpower, 1900 to 1945

In the early 1900s the USA was a land of immigrants and new industry. By 1945 it was the most powerful country in the world.

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A nation of immigrants

Millions of people moved to the USA from Europe. Many arrived through Ellis Island in New York, which opened in 1892.
In 1913 Henry Ford brought in the moving assembly line to build his Model T car. Cars became cheaper, and many more families could afford one.
The 19th Amendment (1920) gave American women the vote.
Prohibition banned the making and sale of alcohol from 1920 to 1933. Gangsters such as Al Capone made fortunes selling it illegally.

Boom and bust

The 1920s were a boom for many Americans, with new goods, radio, cinema and jazz. But farmers and many Black Americans did not share the wealth.
In October 1929 share prices collapsed in the Wall Street Crash. Banks failed and millions lost their jobs in the Great Depression.
Franklin D. Roosevelt became president in 1933 and launched the New Deal: government schemes to create jobs, help farmers and support the poor. The Social Security Act (1935) began old-age pensions.

Into the world

At first the USA stayed out of the Second World War.
On 7 December 1941 Japan attacked the US naval base at Pearl Harbor in Hawaii. The USA joined the war against Japan, Germany and Italy.
In August 1945 the USA dropped atomic bombs on Hiroshima (6 August) and Nagasaki (9 August). Japan surrendered soon after.
The USA ended the war as a superpower, soon facing the USSR in the Cold War.
Worked example

How did the New Deal try to deal with the Great Depression?

  1. The government created jobs through public works such as building roads, dams and schools.
  2. It gave help to farmers and support to the poor and unemployed.
  3. Laws such as the Social Security Act (1935) began pensions, so government took a bigger role in people's lives.

Answer: By using government money and new agencies to create jobs and give help.

Key idea

Immigrants through Ellis Island (from 1892). Ford's assembly line (1913). Women's vote (1920). Prohibition (1920 to 1933). 1920s boom; Wall Street Crash (October 1929); Great Depression. Roosevelt's New Deal from 1933; Social Security Act 1935. Pearl Harbor (7 December 1941) brought the USA into the war; atomic bombs on Hiroshima and Nagasaki (August 1945).

Key words
1945
Auschwitz liberated, 27 January. VE Day, 8 May.
1933
Hitler becomes Chancellor of Germany, 30 January.

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  1. From which year did Ellis Island receive immigrants?

    1. 1492
    2. 1776
    3. 1945
    4. 1892
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    Answer: 1892

    Ellis Island opened in 1892.

  2. Which car did Henry Ford make cheaply on his assembly line?

    1. The Mini
    2. The Model T
    3. The Beetle
    4. The Mustang
    Show the answer

    Answer: The Model T

    The Model T was cheap to build.

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Checked by the GCSE-ready editorial team, 17 October 2026. Last updated 2 October 2026. Spotted a mistake? Tell us and we will fix it.

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