I was going to bring up aircraft carriers as well. The America that ended the war was far more powerful militarily than it was at the start.
At the time of Pearl Harbor, America had eight aircraft carriers in total, with only the Lexington, Enterprise and Saratoga stationed in the Pacific. The Japanese thought that if they could sink those carriers, the U.S. would be forced to sue for peace. And it was certainly lucky that the carriers weren’t at Pearl when the attack happened. But Japan was wrong - America started building the Essex Class carriers, which were larger and better than the 8 that existed before the war, and built 26 of those from 1942 to 1944. They also built a number of smaller carriers. But those Essex class carriers were very good - so good that some of them remained in active service until the mid-1990’s. These were 36,000 ton carriers that in today’s dollars cost a billion dollars each. In comparison, Japan commissioned 16 carriers in total after Pearl Harbor, but most of them were smaller carriers with only five being more than 20,000 tons.
The U.S. never lost a single Essex-class carrier to enemy action in the war. All of Japan’s carriers were sunk except for two, and all but four were sunk by the end of 1944.
The U.S. actually had plans to build 8 more Essex-class carriers, but cancelled them when it became obvious that they weren’t needed. And had America been losing carriers, it could have built dozens more if it needed to.
As an aside, the Japanese did build one monstrous carrier - The Shinano at 62,000 tons. But the thing never saw action - an America submarine sunk it as it was on its way to pick up its first load of Kamikaze bombs.
As another aside, Canada was another WWII power with an immune infrastructure and the capability to build a lot of armaments indefinitely. At the start of WWII Canada’s Navy was tiny: 11 combat vessels, 145 officers and 1,674 men. By the end of WWII Canada had the 3rd largest navy in the world after the Americans and Brits. Its navy included two carriers, five cruisers, twenty-eight destroyers, seventy frigates, and a whole lot of smaller ships.
The point remains that the Axis powers stretched themselves to the breaking point to maintain their war efforts and America outproduced them easily without breaking a sweat.
The scary thing to contemplate is that this situation was known to many of them at the time. Remember Yamamoto’s declaration that Pearl Harbor served only to awaken a sleeping giant. The enemy knew exactly how much production America was capable of and how much America was producing, and knew they had no chance to match it. And yet, they kept fighting. Japan kept fighting until the Bomb stopped them, and Germany didn’t stop fighting until its leadership was captured or dead. Remember that when you think big wars can’t happen any more because people know it’s not in their rational interest. Conflicts have a habit of starting from spirals of events and then becoming chaotic and unpredictable.