You are asking us to compare America's manufacturing capacity during WWII (1941-45), when the country had a population of 140 million - with its population today, which is over a third of a billion?
When our real GPD was about a tenth of what it is now? When semiconductors and solid-state technology and lasers were science-fiction - compared to today?
Regards,
The fact that the US now has about 332 million and a higher GDP of 23.32 trillion vs. $0.203 in 1943 with vast leaps in technology taking place and following in years to come means that the current inability to quickly produce armaments relative to current tech stands in profound contrast to WW2.
Tech development is relative. The rate of increase in the 1940's and beyond was astounding, by the grace of God, Today, due to far far better accuracy and power, the US need not produce anything close to the quantity of armaments of WW2, but it takes years to replace what is given to Ukraine in the proxy war with Putin, while even if going fully onto a war footing the US lacks both the character and ability to endure a protracted war with China, though the latter is now having problems.
In any case, the manufacturing output of the US in WW2 was clearly prodigious. .
American industry provided almost two-thirds of all the Allied military equipment produced during the war. In 1939, the United States Army ranked thirty-ninth in the world, possessing a cavalry force of fifty thousand and using horses to pull the artillery. Many Americans — still trying to recover from the decade-long ordeal of the Great Depression — were reluctant to participate in the conflict that was spreading throughout Europe and Asia....In the wake of Pearl Harbor, the president set staggering goals for the nation’s factories: 60,000 aircraft in 1942 and 125,000 in 1943; 120,000 tanks in the same time period and 55,000 antiaircraft guns. In an attempt to coordinate government war agencies Roosevelt created the War Production Board in 1942 and later in 1943 the Office of War Mobilization. To raise money for defense, the government relied on a number of techniques — calling on the American people to ration certain commodities, generating more tax revenue by lowering the personal exemption and selling government war bonds to individuals and financial institutions. All of these methods served to provide the government with revenue and at the same time keep inflation under control. -https://www.pbs.org/kenburns/the-war/war-production..Wartime production boomed as citizens flocked to meet the demand for labor.
Unemployment, which had reached 25 percent during the Great Depression and hovered at 14.6 percent in 1939, had dropped to 1.2 percent by 1944—still a record low in the nation’s history. ...by 1945, Americans were saving an average of 21 percent of their personal disposable income, compared to just 3 percent in the 1920s....With the war finally over, American consumers were eager to spend their money, on everything from big-ticket items like homes, cars and furniture to appliances, clothing, shoes and everything else in between..... Residential construction companies also mobilized to capitalize on a similar surge in housing demand, Between 1946 and the early 1960s, Levitt & Son built three residential communities (including more than 17,000 homes), finishing as many as 30 houses a day. - https://www.history.com/news/post-world-war-ii-boom-economy
War-related production skyrocketed from just two percent of GNP to 40 percent in 1943. - https://eh.net/encyclopedia/the-american-economy-during-world-war-ii/