Mobilization for World War II affected American society in profound ways. Ironically, participation in the biggest war in all of human history did more to help American society than to harm it (outside, of course, of trauma suffered by many members of the Armed Forces and the tremendous grief suffered by those who lost loved ones in the war).
The most important short-term effect of mobilization for the war was that it finished taking the United States out of the Great Depression. The New Deal had done much to help fix the US economy, but the economy was still not as strong in 1939 as it had been in 1929. After WWII broke out in Europe, the US economy boomed. The economy benefited from producing materiel to sell to England and from the beginning of a US military buildup.
After the US became involved in the war, mobilization continued to change the economy. One of the most famous ways in which this happened was the movement of women into jobs that had been dominated by men. As men left their jobs because they were drafted into (or volunteered for) the military, women stepped up. This changed the role of women in American society, at least in the short term.
This mobilization also had long-term effects. First, mobilization helped to improve the US economy in the long term as well as the short term. For example, during WWII, people could not really spend their money because goods were rationed. This meant that there was a huge amount of savings built up by the end of the war. These savings provided capital to help the US economy boom after the war was over. As another example, mobilization led to the creation of the GI Bill as the war was ending. This law helped send large numbers of ex-military men to college, creating the largest cohort of college-educated men up to that point. These educated men helped make the US economy grow.
Second, mobilization helped change our society. It helped to change the status of women. Women did not generally keep their factory jobs after the war, but they became less happy with the idea that they should stay in the home. This helped bring about a women’s movement that began in the 1950s. Mobilization also helped bring about the push for civil rights. African Americans who served in the military in WWII were less likely to accept segregation. They helped to start what we now know as the Civil Rights Movement.
In all of these ways, mobilization for WWII changed the US economy and society in the short and long terms.
Mobilisation for World War II did drastically transform American society in ways that were almost entirely unprecedented. With its massive population of troops and its status as an economic juggernaut, the entry of the Americans into the global conflict had the effect of tipping the scale in favour of the Allied Powers, who were then in bad need of assistance. It is crucial to note that mobilisation in this case did not merely involve the military and the sending of troops to the battlefront, but also included the channelling of economic resources towards the production of military goods, such as battleships (e.g. the Liberty ships) and ammunition, to support the Allied war effort. In fact, the American economy was doing so well that it was able to meet the demands of the war, while maintaining the current standard of living for the American public - the Americans were not only manufacturing for war, but they were also producing civilian goods, and providing loans to their allies, particularly Great Britain. This was a feat that was only accomplished by the US, whose home front was practically impregnable to possible invasions from the Axis powers.
Such a devotion of economic and military capability to mobilising the American society for war, especially in the former area, brought substantial benefits to the US economy in the long run. The massive demand for military products needed by the Allied troops spurred an increase in contracts for heavy industries in America and allowed these companies to generate much profits for themselves. This led to an economic boom that lasted well into the post-war years, cementing America's position as an economic power to be reckoned with in the global order. The signing of the Lend Lease, which allowed Great Britain to purchase all the goods and resources they needed from the US with no constraints, between the two powers only further accelerated these developments. Such diplomatic moves helped to drive up industrial demand and provided American corporations with greater opportunities to profit from the war.
Another impact that mobilisation had on American society was spurring migrations westwards, which had long-term ramifications for the population demographics of the US. As demand for products increased and the need for American heavy industries to produce all goods at the largest quantities possible arose, manpower shortages emerged. There was a rising need to spread labour and space outwards so that previously unused resources could be fully utilised to meet wartime needs. Large populations of workers began to shift westwards, settling away from densely populated areas to set up new cities. This was especially noted along the east coast. Similarly, a huge increase in the demand in the industrial cities of the north drove many African-Americans, who had previously been concentrated in the south, northwards. Prominent Black communities sprouted and such phenomenon had a large role in changing American politics, as well as demographics - circumstances that were made possible only by the needs of war.
In addition, such high demand, driven by mobilisation, meant that the Americans too began to tap into their mobilisable and economically-viable pool of young women, who were encouraged to take up jobs in traditionally masculine industries as replacements for men that had been conscripted. Women increasingly found themselves exposed to alternative lifestyles, where they had more say and control over their own behaviour and more freedom in society, and this changed the expectations that they had of the roles they had to play. As soldiers returned from war and increasingly expected to have their own jobs back, women grew extremely reluctant to give up the control and benefits they had earned. Such an unleashing of liberal ideas helped pave the way for women towards recognising their own rights in American society.
This was also apparent in Black communities. As demand for more troops increased, African-Americans were also conscripted into the army. This was despite the fact that large portions of the nation were still undertaking the policy of segregation, which saw the Blacks being denied their rights in American society. Increasing politicisation and their rising awareness of the world through their experiences in war made it more obvious how unjust the policy of segregation was. The efforts the Blacks had put into the war also saw them clamouring for greater returns and a recognition of their rights in the post-war years.