No cold war
Russia goes reasonably democratic in 1948 as Stalin drops dead and his associates kill each other off. The US does a traditional disarmament and steadily pays off the national debt like we traditionally do, and it's all over.
We might never go off the gold standard. We sell off our gold supplies to keep the price of gold low, and nobody buys it because after WWII there is no cold war to ever make people flee to gold as a store of value.
Without the cold war would we keep paying for research and development? If we build the Interstate Highway System as a military project every time we have a recession as a countercyclical effort, and keep the FTC to prevent the corporations from restricting production to raise prices, and get rid of tariffs to keep the corporations honest by inducing competition, and maybe get people to join the armed forces by offering college scholarships a la the GI bill so we could keep technological progress going to keep inflation low by increasing productivity.