I’m not sure what prompted me to look at this, but I did. I suppose I’m just tired of Elon Musk (don’t ask) and taking a break. Anyway, here are federal interest payments as a share of GDP since 1960:
It’s hard to see any big warning signs here. This could become a problem if both the deficit and interest rates go up substantially, but as long as Republicans don’t enact another Reaganesque tax cut and inflation stays subdued, that seems unlikely.