US federal debt has consistently overshot forecasts: US federal debt held by the public is up to 100% of GDP, its highest level since peaking near ~106% during World War II. Federal debt held by the public is the portion of US government debt owned by investors, businesses, and foreign governments, excluding intragovernmental holdings such as Social Security trust funds. This metric already exceeds the CBO's January 2017 forecast for this same debt level by ~15 percentage points. Similarly, the CBO's January 2009 forecast projected Debt-to-GDP would reach just ~42% by 2019. The actual ratio instead surged to a record ~78% by 2019, overshooting that estimate by ~36 percentage points. The CBO now projects Debt-to-GDP will rise to ~120% by 2035, though if forecasts continue overshooting by a similar ~15 percentage point margin, the actual ratio could surge closer to ~135%. US debt trajectory may be far worse than current forecasts suggest.