WASHINGTON — The Founding Fathers left one legacy not celebrated on Independence Day but which affects us all. It's the national debt.

The country first got into debt to help pay for the Revolutionary War. Growing ever since, the debt stands today at a staggering $11.5 trillion — equivalent to over $37,000 for each and every American. And it's expanding by over $1 trillion a year.

The mountain of debt easily could become the next full-fledged economic crisis without firm action from Washington, economists of all stripes warn.

"Unless we demonstrate a strong commitment to fiscal sustainability in the longer term, we will have neither financial stability nor healthy economic growth," Federal Reserve Chairman Ben Bernanke recently told Congress.

Higher taxes, or reduced federal benefits and services — or a combination of both — may be the inevitable consequences.

The debt is complicating efforts by President Barack Obama and Congress to cope with the worst recession in decades as stimulus and bailout spending combine with lower tax revenues to widen the gap.

Interest payments on the debt alone cost $452 billion last year — the largest federal spending category after Medicare-Medicaid, Social Security and defense. It's quickly crowding out all other government spending. And the Treasury is finding it harder to find new lenders.

The United States went into the red the first time in 1790 when it assumed $75 million in the war debts of the Continental Congress.

Alexander Hamilton, the first treasury secretary, said, "A national debt, if not excessive, will be to us a national blessing."

Some blessing.

Since then, the nation has only been free of debt once, in 1834-35.

The national debt has expanded during times of war and usually contracted in times of peace, while staying on a generally upward trajectory. Over the past several decades, it has climbed sharply — except for a respite from 1998 to 2000, when there were annual budget surpluses, reflecting in large part what turned out to be an overheated economy.

The debt soared with the wars in Iraq and Afghanistan and economic stimulus spending under President George W. Bush and now Obama.

The odometer-style "debt clock" near Times Square — put in place in 1989 when the debt was a mere $2.7 trillion — ran out of numbers and had to be shut down when the debt surged past $10 trillion in 2008.

The clock has since been refurbished so higher numbers fit. There are several debt clocks on Web sites maintained by public interest groups that let you watch hundreds, thousands, millions zip by in a matter of seconds.