In eighteen thirty-five, the US national debt was exactly zero.
Why it is true
President Andrew Jackson, who hated debt and central banks, managed to completely pay off the federal debt, the only time in the country's history this happened.
Source: Economic History
Would you rather be asked first?
This is the reading side of the site, so the answer is in the sentence above — that is the whole point of it. Test yourself works the other way round: the question comes on its own, and the fact and the explanation only appear once you have answered.