In 1946, a year after WWII ended, >5 million American workers went on prolonged strikes in numerous industries and public utilities. The American strike wave of 1945–1946 became the largest series of labor strikes in American history.
During WWII, the National War Labor Board granted unions closed shop agreements in exchange for maintaining labor discipline throughout the war. Throughout the war, various wildcat strikes over work discipline, company policy or firings did occur, but they were not prolonged or massive.
After the war, demand for increased wages (no longer frozen by the Stabilization Act of 1942) lead to the onset of larger strikes.
American Labor Strikes in 1945
10,500 film crew workers
43,000 oil workers
225,000 United Auto Workers
American Labor Strikes in 1946
174,000 electric workers
750,000 steel workers
340,000 coal miners
250,000 railroad engineers and trainmen nationwide
120,000 miners, rail and steel workers in the Pittsburgh region
Other strikes included railroad workers and “general strikes across the country.
~4.3 million workers participated in the strike wave of 1945-46.
In 1947, over President Truman’s veto, Congress passed the Labor Management Relations Act (Taft-Hartley Act) that restricts powers and activities of labor unions. The act is still in effect today.