This is the wrong question. When does federal debt increase rate become unsustainable? As common wisdom states, federal debt is public surplus. It's the set of

This is the wrong question. When does federal debt increase rate become unsustainable? As common wisdom states, federal debt is public surplus. It's the set of things that the federal government has invested funding in that haven't been liquidated. This includes roads, streetlights, parks, power substations, etc. The relevant question for our economy is how quickly is the federal government spending, and what is the value created from that spending?