Hundreds of thousands of US employees have headed back to work following a 16-day government shutdown and extending the US debt limit.

Tourist attractions across the country had been closed to the public following failure by the United States Congress to agree a new budget, forcing the shutdown.

Sites affected by the shutdown included the Statue of Liberty, the Grand Canyon, 19 museums/galleries from the Smithsonian Institution, Bunker Hill Monument, Independence Hall, the National Zoo, Alcatraz, Yosemite National Park and the Washington Monument to name just a handful.

In the US’s national parks, 24,645 people were directly affected, with essential staff such as fire management, law enforcement and emergency responders the only ones kept on duty. State governors said that the closures have severely impacted on local communities and businesses around the parks, which rely on tourism to survive.

The shutdown affected 4,202 employees at the Smithsonian Institution alone, with just 688 being retained during the shutdown “to protect life and property.”

During the shutdown employees affected were forced to go on annual leave without pay, though a few days into the shutdown congress passed a law ensuring they would receive back pay.

Speaking after the Senate had passed the bill on Wednesday evening, President Barack Obama warned that US lawmakers must "earn back the trust of the American people".