Each year the Superintendent, under discretionary authority, establishes certain amendments to the Code of Federal Regulations (36 CFR 1.7(b)) that designate certain closures, permit requirements and other restrictions in the park. That document is available as a PDF file here:
A federal law passed by Congress took affect on February 22, 2010 and allows anyone who can legally possess firearms under applicable Arizona state laws, to legally possess firearms in this park. Although Arizona State law allows people to possess firearms, all other federal regulations restricting the use of the firearm still apply and include, but are not limited to:
Firearms may not be discharged in this National Park service unit and should not be used as a wildlife protection strategy.
Firearms may not be possessed in certain facilities in this park (such as visitor centers, government offices, etc.) Those facilities where you may not possess a firearm are posted with signs at all public entrances.
It is the responsibility of visitors to understand and comply with all applicable firearms laws before entering this park. Additional information concerning Arizona State regulations can be accessed on the following web pages:
Home page: http://az.gov/
Concealed Weapons: http://www.azdps.gov/Services/Concealed_Weapons/
State Reciprocity: http://www.azdps.gov/Services/Concealed_Weapons/Reciprocity/
Last updated: December 2, 2018