The significant U.S. legislation passed under Franklin D. Roosevelt during the Great Depression was the Social Security Act of 1935. This landmark legislation established a social safety net for the elderly, unemployed, and disabled, recognizing the need for government intervention during economic crises. The act provided pensions to retired workers and created unemployment insurance, fundamentally altering the relationship between the government and American citizens by formalizing government responsibility for social welfare. It laid the groundwork for future welfare programs and remains a key component of the U.S. social safety net today.