Government debt allows states to finance spending today while spreading the cost over future years. Borrowing can be sensible when it finances productive infrastructure or stabilizes the economy during a downturn.
Debt becomes more difficult when interest costs consume an increasing share of public revenue or when borrowing finances spending without improving future capacity. The sustainability of debt depends on growth, interest rates, fiscal policy and investor confidence.
The key is not a single debt number. It is the relationship between debt and the economy’s ability to service it over time.