The hump between 29 and 45 shows that DEflation is just as dangerous as INflation.
That was an INfalatioany period. The dollar was buying less from 1929 to the end of the war. Prices were going up, and there were shortages. From 29 to, say, 37 or so, the government was doing what it is doing now, doing everything it can to keep crop, commodity, wages( some ) high, even though a lot of people had no work and could not afford those INFLATED prices. ( They said the Depression wasn’t bad if you had a job ) The late 30’s though the war was total government printing money, chasing totally socilist/command manufacturing, so goods and service prices soared and savings became worth less. Like now. Prices kept, or attempted to be kept high, savings at zero.