The plan put forward by the interior department, which supervises America's 390 national parks and 548 wildlife refuges, would repeal a decades-old rule banning guns in the park system.
"The safety and protection of park and refuge visitors remains a top priority," interior secretary Dirk Kempthorne said in a statement announcing the rules change.
Conservative politicians have joined the National Rifle Association, the largest gun-rights group in the country, to press for weapons in the parks before a new - and possibly Democratic - president takes office next year. Supporters of the ban argue that park visitors need protection from animals or criminal attacks.
Although threats to rangers in national parks have risen according to some independent research, the sites remain highly safe for visitors. The chance of becoming a crime victim in an official US refuge is 1 in more than 708,000, park service advocacy groups have noted.
Under the new rules, concealed weapons would remain prohibited in California, as well as other states that have passed separate laws against bringing guns into parks.
But that exception is prompting critics, such as Democratic senator Dianne Feinstein, to question what happens when one national park crosses a line between two states with two different laws.
"This sort of inconsistency would be an open invitation to poachers, would be almost impossible to enforce, and would seriously place public safety at risk," Feinstein said.
The park service advocacy groups, representing rangers and frequent visitors to the scenic areas, have condemned the rule as a politically motivated sop to the right wing.
"This proposed regulation increases the risk to visitors, employees and wildlife rather than reducing it," Bill Wade, chairman of the coalition of national parks retirees, said.
© 2008 The Guardian