The end of the 35-day-long partial government shutdown means thousands of furloughed workers across the state are returning to work, and, at some point, receiving back pay.

The shutdown — the longest in U.S. history — ended Friday when President Donald Trump backed off his demand that Congress commit $5.7 billion for a U.S.-Mexico border wall before federal agencies could resume work. All or parts of multiple federal agencies were affected, with some employees furloughed and others forced to work without pay.

Steven Calder, an inspector for the Environmental Protection Agency who was furloughed during the shutdown, said he feels a mixture of frustration and relief at returning to work Monday.

"[I'm] frustrated that all federal employees that were out on furlough were basically pawns on a political policy issue," said Calder, who is president of the union that represents Region 1 EPA employees. He added, "So having that behind us is great. I'm hoping that we don't have this issue in three weeks and that the political people involved in all this will end up resolving the issues so we're not put out of work and put back on furlough. There's no reason for it. It only hurts the economy. It hurts the individuals that are out on furlough and it just makes no sense."

The spending bill Trump signed on Friday funds the government agencies that had been shut down for 35 days, only until Feb. 15. On Sunday, acting White House chief of staff Mick Mulvaney said that Trump is prepared to shut down the government again if he doesn't receive funding for the border wall.

"I am looking forward to getting back to work and in particular, getting our paycheck," Calder said, though he said he doesn't yet know exactly when he will receive his back pay. The Trump administration has promised to get the back pay out to federal workers as soon as possible.

Michael Creasey, the general superintendent of the National Parks of Boston, was one of the few National Park Service employees in the city who worked during the shutdown. The parks reopened on Saturday, and while Creasey said the mood was joyful, it will take time for things to return to normal. It could take weeks for his office to catch up on back-logged work from the past month, he said.

"It's not like you can flip the switch off and flip it back on and you're back and running," Creasey said. "It takes a long time to get people back to where they were."

Material from the Associated Press was used in this report.