About 10,000 federal employees in Puerto Rico, a US commonwealth, were affected Tuesday by the shutdown, where there was practically no activity at several of the agencies that are directed from Washington.
The most noteworthy effect occurred in San Juan, where Fort San Felipe del Morro and Fort San Cristobal, two of the city's - and the island's - main tourist attractions, remained closed.
The El Yunque National Park -- the only tropical rainforest in the US National Forest System -- also could not be visited by tourists due to the government shutdown.
The Social Security offices did not open, and there was also no activity at the facilities of the Internal Revenue Service or the Environmental Protection Agency.
The US District Court for the District of Puerto Rico opened its doors in San Juan, only to attend to cases that have already been ruled on, whereas other regular judicial activities were halted.
The top FBI official in Puerto Rico, Carlos Cases, announced that activity at his agency would continue normally, just as occurred at the Veterans Administration offices.
There was activity at Puerto Rico's Department of Family Affairs, which administers the Nutritional Assistance for Puerto Rico program, and also at the offices that issue visas and passports.
The president of the local office of the American Federation of Government Employees, Alejandro Alvelo, said in remarks to radio station WKAQ that the federal government shutdown will directly affect about 10,000 people on the island.
Alvelo said that Tuesday many federal employees came to their jobsites only to be told about the partial halting of activities there.