The Glass-Steagall Act, established in the 1930s, had a significant historical impact on the American banking system by separating commercial banking from investment banking. Its implementation aimed to reduce conflict of interest and mitigate risky financial ventures that contributed to the 1929 stock market crash and the Great Depression. By prohibiting banks from acting as both commercial lenders and investment firms, it sought to stabilize the financial system. However, the repeal of key provisions in the 1990s led to increased risk-taking and was cited as a contributing factor to the 2008 financial crisis, highlighting ongoing debates about financial regulation.