<P> Historically, the US public debt as a share of gross domestic product (GDP) has increased during wars and recessions, and subsequently declined . The ratio of debt to GDP may decrease as a result of a government surplus or due to growth of GDP and inflation . For example, debt held by the public as a share of GDP peaked just after World War II (113% of GDP in 1945), but then fell over the following 35 years . In recent decades, however, aging demographics and rising healthcare costs have led to concern about the long - term sustainability of the federal government's fiscal policies . </P> <P> On November 7, 2016, debt held by the public was $14.3 trillion or about 76% of the previous 12 months of GDP . Intragovernmental holdings stood at $5.4 trillion, giving a combined total gross national debt of $19.8 trillion or about 106% of the previous 12 months of GDP; $6.2 trillion or approximately 45% of the debt held by the public was owned by foreign investors, the largest of which were Japan and China at about $1.09 trillion for Japan and $1.06 trillion for China as of December 2016 . </P> <P> The United States government has continuously had a fluctuating public debt since its formation in 1789, except for about a year during 1835--1836 . To allow comparisons over the years, public debt is often expressed as a ratio to gross domestic product (GDP). </P> <P> The United States public debt as a percentage of GDP reached its highest level during Harry Truman's first presidential term, during and after World War II . Public debt as a percentage of GDP fell rapidly in the post-World War II period, and reached a low in 1974 under Richard Nixon . Debt as a share of GDP has consistently increased since then, except during the presidencies of Jimmy Carter and Bill Clinton . Public debt rose during the 1980s, as Ronald Reagan cut tax rates and increased military spending . It fell during the 1990s, due to decreased military spending, increased taxes and the 1990s boom . Public debt rose sharply in the wake of the 2007--2008 financial crisis and the resulting significant tax revenue declines and spending increases . </P>

How long has the us had a national debt