U.S. families—by defaulting on their loans and scrimping on expenses—shouldered a smaller debt burden in 2010 than at any point in the previous six years, putting them in position to start spending more.

Total U.S. household debt, including mortgages and credit cards, fell for the second straight year in 2010 to $13.4 trillion, the Federal Reserve reported Thursday. That came to 116% of disposable income, down from a peak debt burden of 130% in 2007, and the lowest level since the fourth quarter of 2004.

With...