A protracted government shutdown would hurt many states, but particularly Puerto Rico, where federal funding makes up 40% of all government revenue, Reuters reports.
The island's economy has been weak in recent years, with Puerto Ricans leaving to the U.S. for better opportunity.
Half of Puerto Rico's 10,000 federal government workers will be affected.
Even the temporary loss of as many as 5,000 jobs could be enough to raise the unemployment rate on an island with fewer than 900,000 jobs. The unemployment rate is already the highest of any U.S. state or territory at 13.9 percent. And the economy, which last year emerged briefly from recession after six years, contracted by 5.4 percent in August from its level a year earlier.