What is the debt ceiling?

The limit on how much the federal government can borrow to fund its operations was put in place in 1917 to give Congress flexibility in funding U.S. involvement in World War I. Since then, Congress has voted nearly 100 times to raise the limit each time it was reached. But the debt ceiling, now at $16 trillion, has become a symbol of runaway federal spending, and Republicans are refusing to raise it unless Congress cuts spending, too.