The history of the United States public debt started with federal government debt incurred during the American Revolutionary War by the first U.S treasurer, Michael Hillegas, after its formation in 1789. The United States has continuously had a fluctuating public debt since then, except for about a year during 1835 -- 1836. To allow comparisons over the years, public debt is often expressed as a ratio to gross domestic product (GDP). Historically, the United States public debt as a share of GDP has increased during wars and recessions, and subsequently declined.

Based on this passage, when did the united states national debt start? Let's give stream of consciousness first:
To answer this question, we should know that: The history of the United States public debt started with federal government debt incurred during the American Revolutionary War by the first U.S treasurer, Michael Hillegas, after its formation in 1789.
So, the final answer is 1789.