On February 22, 2010 the new law allowing citizens to carry firearms in national parks in accordance to state laws and procedures went into effect.
Visitors may possess firearms within a national park unit provided they comply with federal, state, and local laws. Please remember that federal law prohibits firearms in certain park facilities and buildings. These places should be marked with signs at public entrances.
More info and list of parks per the National Park Service:
http://www.nps.gov/nero/firearms/PA/index.htm
Parks:
Allegheny Portage Railroad National Historic Site
Delaware Water Gap National Recreation Area
Edgar Allan Poe National Historic Site
Eisenhower National Historic Site
Fort Necessity National Battlefield
Friendship Hill National Historic Site
Gettysburg National Military Park
Hopewell Furnace National Historic Site
Independence National Historical Park
Johnstown Flood National Memorial
Steamtown National Historic Site
Thaddeus Kosciuszko National Memorial
