American Bison graze at the Grand Teton National Park.

Danny Lehman | The Image Bank | Getty Images

Congress is trying to come up with more money to give the aging national parks a facelift in honor of the country's 250th birthday this year. President Donald Trump talks about the importance of federal facilities looking good, while his budget proposal slashed funding for the National Park Service.

Republican lawmakers are searching for revenue sources including establishing tolls on federally operated roads in the Washington area used daily by tens of thousands of commuters and by hiking fees to visit national parks for visitors from outside the U.S.…