European nations had been at war for three years when the United States entered World War I in April 1917. The Federal government struggled to increase production, slow labor turnover, and regulate hours and working conditions. More women worked in traditionally male occupations such as shipbuilding and armaments manufacture. African Americans moved to northern cities for greater economic opportunity. Strike levels during the war reached new, unheard of highs. In response, the Federal Government created a National War Labor Board made up of representatives from labor, business, and the public, which settled labor disputes. Its rulings helped organized labor secure gains.