So firstly, let’s not worry about whether to call the American economy planned or not, let’s just describe what happened in the wartime Economy and let the chips fall where they may.

Firstly, A war economy was imposed by changes in government policy, done for the most part by Roosevelt's administration with Congress’s grudging consent and loose oversight. Congress gave broad powers to the Administration but did not carefully define them. The administration created, in classic Roosevelt/New Deal style, a complicated and shifting mix of Boards and Agencies with interlocking and overlapping functions. There was the War Production Board, The Office of Price Administration, The Office For Emergency Management, the Office of Economic Stabilization, the Board of Economic Warfare, War Manpower Commission, the Selective Service System, National War Labor Board, The War Department itself, The Navy Department, the Combined Raw Materials Board, Combined Food Board, the United States Office of War Information and phewww… I’m forgetting some important boards and agencies but you get the point. There was a huge bureaucratic maze in Washington to run the economic side of the war.

What were the powers of these boards taken as a whole system, however inefficient and confusing? They had extremely wide powers. They could set prices. Conscript people into the Armed Forces. Allocate raw materials to firms. Issue government contracts for armaments and things like artificial rubber needed for military production. They could have factories built. They could sell or lease these factories to defense contractors. They could ration food. The could ration consumer goods. They could decide where military bases and buildings would be built. They could more or less print money and change taxation rates and policies. However, they were subject to the political system, and congress in particular could make a lot of trouble for them. If they pissed off a privileged constituency like Farmers, Congress would, and did pressure the executive branch boards to reverse the objectionable decision. Congress also did exercise a degree of helpful oversight in the Truman Committee.

The net effect of this system was that the executive branch of the U.S. government had effective control of most of the economy. No firm or factory could just decide to produce, say, refrigerators for the civilian market. A board wouldn’t give such a firm an allocation of steel, copper or plastic. The selective service would draft the majority of its workers. The office of price administration would set a low price so that these goods wouldn’t be profitable to sell. In effect, most industrial firms simply had to either convert to war production or get permission from the government to continue civilian production. In some cases government orders explicitly forbid production of certain civilian goods.

So firms absolutely scrambled to convert to war production, or go out of business. Big Automobile companies converted to warplanes. Railroad firms converted to tanks. Small manufactures made smaller weapons or became subcontractors and made sub-assemblies of larger weapons for the war effort. Naturally there were boards and services to help firms retool for war production and find their new niche in the war economy. As you might expect, firms did everything they could to influence the War Boards and amass economic power in their industries. Washington became infested with “Dollar a Year Men” or lobbyists for corporations acting as unpaid (by the government) expert consultants for various boards.

In 1945 (or even earlier) before the war ended, this process began to reverse, and government contracts dried up while restrictions eased. The government’s experience at the end of WWI having shown that there were political consequences to botching the transition back to peacetime economics. The armed services pushed back against this process to a degree, and there was the usual ugly Washington political decision making process.

So does all this add up to a planned economy? For me, it sure does. They had a central planning apparatus, which (dated but colorful) historial Bruce Catton called “The War Lords of Washington” in his book title. However, I think it can be argued that the U.S. Economy was probably the least centrally planned amongst the belligerents. The U.K. was less squeamish about using very strict rationing and conscription and accepted less pushback from constituencies. Soviet and German systems used widespread coercion, pillage and outright forced labor while having official “Five/Four Year Plans.” I guess you could say that the U.S. had “Central Planning Lite”, but the U.S. has never been as centrally planned as it was between 1941-45.

Source: Klein, Maury "A Call to Arms: Mobilizing America for World War Two"