The Grand Canyon, Statue of Liberty and other tourist sites are reopening after state officials reached deals with the federal government.
Arizona and New York will fund the attractions from their own budgets, and are unlikely to be reimbursed.
Other states are now weighing up whether they can justify the outlay of cash to keep their parks open.
The tourist sites closed after Congress failed to agree a budget, forcing many government services to shut down.
New York Governor Andrew Cuomo described the Statue of Liberty as an “international symbol of freedom” and promised he would not allow “dysfunction” in Washington to keep it closed.
New York will have to pay out about $60,000 a day to keep the Statue of Liberty open.
Arizona Governor Jan Brewer said: “I’m gratified the Obama administration agreed to reverse its policy and allow Arizona to reopen Grand Canyon, Arizona’s most treasured landmark and a crucial driver of revenue to the state.”
Arizona will pay almost $100,000 a day to keep the Grand Canyon open, initially for the next seven days.
Analysts estimate that the Canyon brings in roughly 18,000 visitors each day during the current peak season, and revenue of roughly $1 million.
Elsewhere, South Dakota worked out a deal with corporate donors and the National Park Service to reopen Mount Rushmore on Monday.
And Utah and Colorado have also reached deals to keep their parks open.
Interior Secretary Sally Jewell said in a statement the states had found a “practical and temporary solution” that would “lessen the pain for some businesses and communities”.
The partial government shutdown, which has sent home hundreds of thousands of government workers on unpaid leave, began on October 1.
Republicans have refused to pass a new budget unless President Barack Obama agrees to delay or eliminate the funding of the healthcare reform law of 2010.
The White House has repeatedly said it would not undermine the law, known as Obamacare, nor negotiate over larger budget matters, until Republicans vote to end the threat of default.
Officials say about 15,000 workers in the private sector have already been laid off as a result of the shutdown.
As the well as the shutdown, the US is heading towards default if it does not raise its debt limit by October 17.