How did mobilizing the economy help end the great depression?

Answer 1

The basic idea is that the economy was in a "trap" because of the Great Depression. As unemployment rose, people's incomes fell. As income fell, people spent less, which led to further closing of firms and layoffs. In other words, the economy entered a vicious cycle, where unemployment kept rising, and national income kept falling.

The way out such a vicious cycle or trap is have the government spend like crazy to try and stimulate national income. The hope is that eventually the vicious cycle becomes a virtuous cycle, where incomes start rising, demand for goods start to increase also, and firms start hiring again to fill new orders.

Answer 2

It forced the U.S. government to have a budget deficit. During the Depression, U.S. government maintained a nearly-balanced budget (1929, 1930, and 1937 were years of large budget surplus, while during the rest of Depression there was a mild deficit), with both receipts and expenditures in the $8-10 billion range. In 1944, in contrast, government receipts increased to $49 billion, while expenditures ballooned to almost $75 billion.