Once the war in Europe had begun in 1939, there was a need for new factories to be built in the USA.
Businesses were allowed to provide weapons and supplies to Britain.
The supply of weapons increased even more after the 1941 Lend-Lease Act.
The act then allowed the US government to provide an almost unrestricted supply of aid to its allies in Europe
Lend-Lease Act - An American law that allowed the president to send military aid to countries fighting in a war
Lend-Lease Act - An American law that allowed the president to send military aid to countries fighting in a war
To be able to provide military aid to countries fighting in a war, President Franklin D Roosevelt set up the War Production Board in January 1941
This was run by the industrialist Henry J Kaiser, who had also run the Tennessee Valley Authority (TVA)
The board supervised the production of $183 billion worth of weapons and supplies
It also had to ensure that industries could shift from civilian to wartime production
For example, it helped a tractor factory to convert to building tanks instead
Big businesses were then brought in, to focus on certain war products
For example, the car manufacturing company General Motors was responsible for making millions of machine guns and employed an extra 750,000 people during the war
The Ford car factory in Indiana was producing more weapons than the entire country of Italy by 1944
There were also longer lasting effects of the war on the industry
In 1937, the defence industries were responsible for less than 1.5% of the USA’s income.
However, by 1945, this had risen to 50%
There was also growth among new industries and businesses that had been stimulated by the war
One example is the pharmaceutical industry, which had been boosted by the production of penicillin to heal soldiers wounded in combat
By the end of the war, the US had one of the most powerful economies in the world
The war quickly ended the unemployment crisis caused by the Great Depression in the 1930s
This was because the demand for industrial products increased beyond anything US industry had ever needed to manufacture before
There were 8.1 million unemployed people in the USA in 1940 but only just over 1 million by 1945
Around 16 million people served in the armed forces and around 14 million people worked in factories on the home front by the end of the war
This included almost 4 million workers, many of them African Americans, who migrated from the southern states to work in the factories in the north and the west of the country
Additionally, around 7 million women were added to the workforce
Many of them were employed in engineering and electronics roles, which they had traditionally been excluded from before the war
There was also a large increase in the number of teenage boys in employment, from around 900,000 14- to 18-year-olds in 1940 to 3 million by 1944
President Roosevelt said throughout the war that he wanted the USA to become the “arsenal of democracy”
By this he meant that he wanted the country to make weapons for the Allies (Britain, the Soviet Union and later the USA itself) and also beat the armies of the Axis (Germany, Japan and Italy)
By 1944, the USA was producing half of all of the weapons being used in the war
By 1945, the USA was responsible for half of all of the products being manufactured in the world.
As the Cold War with the Soviet Union emerged and developed throughout the late 1940s, military spending continued to increase
In 1948 the US government spent $11 billion on defence, but by the end of the 1950s this had increased to $50 billion per year
The mass development of new weapons, such as atomic bombs, was partly responsible for this huge increase
California benefitted from an increase in spending on scientific and technological research at institutions such as Caltech - the California Institute of Technology
As a result, the state eventually gained the expertise to become the centre of the USA’s computer industry