WHY IT MATTERS: Debt

[...] rapidly growing spending on federal health care programs like Medicare and the drain on Social Security balances caused by the rising tide of baby boomers could squeeze out other spending, on roads, education, the armed forces and more.

Trump has also shown no interest in curbing expensive benefit programs like Medicare and has actually criticized prior Republican efforts to balance the budget.

[...] she'd turn around and spend it on college tuition subsidies, infrastructure and expansion of President Barack Obama's health care law.

If elected, Clinton is expected to face a hostile GOP-controlled House, making her goal of tax increases for new spending highly unlikely to be achieved, even if Democrats take back the Senate.

[...] as debt continues to grow, economists fear rising interest rates are inevitable, as the government's demand to borrow competes with private borrowers needing capital for investments.

If debt slows the economy down, tax revenues would fall and create even more pressure on the budget and raise the possibility of a European-style fiscal crisis.