美债的历史演进与当下困局：美国系列深度研究之三

Debt Growth and Historical Context - The U.S. federal debt has increased significantly, from $10.6 trillion at the end of Obama's term to $36.2 trillion at the end of Biden's term, with an acceleration in growth rates[3][22] - The first $12 trillion took over 200 years to accumulate, the second $12 trillion took about 10 years, and the third $12 trillion took less than 5 years[22] - As of August 11, 2025, the U.S. debt surpassed $37 trillion[22] Interest Burden and Fiscal Impact - Net interest expenditure for FY 2024 is projected to reach approximately $881.1 billion, a year-on-year increase of 33.9%, accounting for over 13% of total expenditures[4][22] - Each percentage point increase in interest rates could result in an additional $360 billion in refinancing costs annually[4][22] Current Challenges Facing U.S. Debt - The federal debt for FY 2024 is $35.5 trillion, with a debt-to-GDP ratio of 123%, which is lower than Japan (220.8%) and Greece (181.6%), but higher than Germany (60.0%) and France (108.6%)[11][37] - The average annual debt growth from FY 2022 to FY 2024 exceeds $2.3 trillion, approximately $64.3 billion per day, doubling the growth rate from FY 2017 to FY 2019[12][43] - Mandatory spending, including Medicare and Social Security, constitutes 60.1% of total expenditures in FY 2024, making cuts difficult[12][44] Political and Economic Pressures - Political motivations favor fiscal stimulus to maximize voter support, with 90% of surveyed individuals indicating the importance of Social Security in voting decisions[12][46] - The recent "Big and Beautiful" tax and spending bill is expected to increase the debt ceiling by $5 trillion, potentially adding $3.4 trillion to the deficit over the next decade[13][22]