PROVIDENCE, R.I. (AP) — In Philadelphia, pension costs doubled in a single decade. Cities in Rhode Island dimmed streetlights, raised taxes and put off road repairs. Stockton, Calif., fell into bankruptcy.

Unpaid bills from decades of retirement promises made to public workers, combined with a lackluster economy and steep Wall Street losses, have built up a financial mountain that threatens to overwhelm budgets and operations in cities and counties across the country.