Bad Man From Bodie wrote:... Last I checked, all National Parks in the United States of America are located in the Untied States of America...
And that is one of the reasons the rule change was enacted -- to help reduce the 'patchwork quilt' of firearm regulations on public lands. In many cases the various Federal public lands are commingled and intermingled, with no obvious markings on the ground to identify when you walk from one to the other.
Before: National Parks no guns.
National Wildlife Refuges Some OK, some not, depends on hunting season
National Forests firearms OK, follow local law
BLM public lands firearms OK, follow local law
COE, BOR lands firearms OK with a few exceptions, follow local laws.
Now: Follow local laws regardless of which Federal public lands you are standing on.
The 'Now' makes more sense and is easier for the owner of the public lands to stay legal.