The Office of Management and Budget estimates that in the absence of massive cuts in Social Security, Medicare and other programs, or an equally massive tax increase, the national debt will rise to 77% of GDP in 2020, 100% of GDP in 2030 and more than twice GDP by 2050. Economists are divided on the point at which the federal debt becomes a meaningful burden on the economy. A recent paper by economists Carmen Reinhart and Kenneth Rogoff suggests that historically growth has not suffered significantly until debts reached 90% of a nation’s GDP.

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— What is the National Debt? | Capital Gains and Games