Key takeaways: History shows the US is unlikely to achieve the required 6.9% average nominal GDP growth annually over the ten-year budget horizon needed to stabilize its debt-to-GDP ratio while running the primary deficits set in Trump’s One Big Beautiful Bill Act. Slowing US population growth and the exit of baby boomers from the labor market implies strong economic growth does not necessarily reduce the deficit one-for-one: growth of the largest cost center for the government (entitlement programs) will structurally outpace its revenue base (tax receipts). The growth risk underlying US debt sustainability is markedly asymmetric and skewed to the downside. This implies yield curve steepening pressures will persist, and any indication of softer growth should see a sharp acceleration in steepening momentum.