The Neutrality Acts were laws passed in 1935, 1936, 1937, and 1939 to limit U.S. involvement in future wars. They were based on the widespread disillusionment with World War I in the early 1930s and the belief that the United States had been drawn into the war through loans and trade with the Allies.
The 1935 act banned munitions exports to belligerents and restricted American travel on belligerent ships.
The 1936 act banned loans to belligerents.
The 1937 act extended these provisions to civil wars and gave the president discretionary authority to restrict non-munitions sales to a "cash‐and‐carry" basis (belligerents had to pay in advance then export goods in their own ships). (These bills were signed and publicly applauded by President Franklin D. Roosevelt, although he complained privately that they limited presidential authority.)
The 1939 act, passed with President Roosevelt's active support in November under the shadow of the European war, banned U.S. ships from carrying goods or passengers to belligerent ports but allowed the United States to sell munitions, although on a "cash‐and‐carry" basis. Roosevelt further eroded neutrality over the next two years, trading surplus U.S. destroyers to Britain for access to naval and air bases and providing U.S. military equipment to enemies of Germany and Japan under the Lend‐Lease Act. Congress repealed the Neutrality Acts on 13 November 1941, officially ending any form of neutrality.
Although seen as the high tide of interwar isolationism, the neutrality legislation of 1935-37 had minimal impact on U.S. defense planning. The 1939 act encouraged combat testing of U.S. equipment by Allied forces, but also created shortages as U.S. production initially was unable to meet requirements of both Allies and expanding U.S. forces.