<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 , aging demographics and rising healthcare costs have led to concern about the long - term sustainability of the federal government 's fiscal policies . The aggregate , gross amount that Treasury can borrow is limited by the United States debt ceiling . </P>
<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 , aging demographics and rising healthcare costs have led to concern about the long - term sustainability of the federal government 's fiscal policies . The aggregate , gross amount that Treasury can borrow is limited by the United States debt ceiling . </P>
the level of the national debt is limited by
the level of the national debt is limited by
debt ceiling
debt ceiling