Puerto Rico’s long-simmering debt crisis owes much to an economy that has been shedding jobs for years. And blame for that, economists say, stems in part from how the island operates under the same wage rules as the more prosperous 50 states.

The commonwealth is subject to the federal minimum wage of $7.25 an hour, even though local income and productivity are significantly lower than in Mississippi, the poorest American state. The minimum wage in Puerto Rico is equal to 77% of per capita income, compared with 28% in the U.S....