Uh, the economy was producing for war in many areas by 1938. Those Naval battleships at Pearl Harbor didn't simply build themselves, the Army didn't create millions of rifles out of thin air in 1941, etc.

Rationing was required because the government was directing available resources to war production, not because the economy was shit. People could afford food just fine throughout much of WWII, if only the shops had been allowed to sell it to them.

The rationing and price controls wouldn't have been needed if we hadn't been in such a hole at the start of the war. We did produce, but our national production in 1947 was actually 17% higher than in 1941. That is a pretty sad considering the amount of government war spending.