Carlos Lozada summarizes a research paper by Hugh Rockoff: "The Economics of World War I". (Lozada is a journalist contributing to an National Bureau of Economic Research digest of its sponsored research - Lozada's summary has a link to the original paper).
Lozada summarizes Rockoff's analysis of the macroeconomic and financial impacts of the war. I'll just quote two paragraphs on the impact of the war on post-war ideas about economic planning.
The actual planning effort during the war was relatively limited:
"As part of the war effort, the U.S. government also attempted to guide economic activity via centralized price and production controls administered by the War Industries Board, the Food Administration, and the Fuel Administration. Rockoff judges that the overall impact of these programs on reallocating resources was "rather small." Timing played a role, since some of the agencies were only established once the United States entered the war, and they took time to begin fulfilling their roles. Also, management problems emerged. For example, the War Industries Board attempted to create a "priorities system" for determining the order in which producers would fill government contracts for industrial goods. Unfortunately, all policymakers gave their order the highest rating ("A"). Leaders then created several higher priority ratings (such as "A1"), with much the same result. "Replacing price signals with priorities is not as simple as it sounds," surmises Rockoff."
But many post-war thinkers looked to this effort as a model for future responses to crisis:
"In matters of economic ideology, Rockoff argues that, although the U.S. government took on such an active role in economic affairs during the war, this evolution did not ratchet up the government role in peacetime. Subsequent increases in federal spending resulted mainly from war-related matters (such as veterans' benefits), and the most of the wartime regulatory agencies soon disappeared due to the efforts of conservative politicians. Nevertheless, the successful wartime experience "increased the confidence on the left that central planning was the best way to meet a national crisis, certainly in wartime, and possibly in peacetime as well." This view became increasingly important after the Democrats reached power during the Great Depression. "Almost every government program undertaken in the 1930s reflected a World War I precedent," explains Rockoff, "and?many of the people brought in to manage New Deal agencies had learned their craft in World War I." The author concludes that the scope and speed of government expansion in the 1930s were likely greater because of the impact of the war on the world view of new economic and political leaders, who in turn inspired future generations of reformers. "For America, to sum up," writes Rockoff, "the most important long-run impact of the war may have been in the realm of ideas." "