Free park admission Sunday for National Park Service Founders Day

Sunday is National Park Service Founders Day. It marks the 103rd anniversary of the creation of the National Park Service.

To mark the anniversary, all national parks are free Sunday, including Roanoke's Blue Ridge Parkway. 

The day honors the park service's preservation and conservation efforts. 

The service, which is part of the interior department, started with 35 parks and monuments. The service now oversees 400 sites across all 50 states, U.S. territories and Washington, D.C. 

Combined, they add up to 84 million acres.