http://www.nps.gov/grca/parkmgmt/lawsandpolicies.htmFederal law also prohibits firearms in certain facilities in this park; those places are marked with signs at all public entrances.
No signs on the buses carry away.
ETA: Oh, wait ... just found this (emphasis mine);
http://www.nps.gov/grca/parkmgmt/upl...arks2-2010.pdfGuns may not be allowed on shuttle buses,
ferries or boats within certain national
parks, depending on the state.