In 2008, the subprime crisis that began in the United States had a severe impact on the global economy including the United States. After several rounds of policy adjustments since the crisis, especially stimulated by President Trump's tax cuts, the U.S. economy has miraculously recovered strongly and continued to grow, and may create the first growth cycle in history. This paper combs through the influential economic policies in the history of American economic development, including Coolidge prosperity, Reagan's supply-side revolution and Clinton's new economic period. It also examines the role and impact of supply-side reforms such as tax cuts and deregulation on American economy. Through data analysis, we can find that the traditional momentum represented by investment contributed to this time’s recovery of the U.S. economy. At the same time, the new driving forces supported by new energy and new technology are also bright spots. Together, they have provided a powerful driver for American economic growth. However, with the weakening of the cyclical forces of the U.S. economy, the impact of continuous increase on interest rate, the impact of trade war between China and the U.S. on its exports, and the hidden dangers of the Trump administration, this paper argues that the factors affecting the sustainable development of the U.S. economy are accumulating, and the pressure of economic downturn and financial risks are increasing.
