Interior Secretary Dirk Kempthorne proposed the rule in response to letters from 51 United States senators  42 Republicans and 9 Democrats  who asked that the current rule be changed. The current rule, the senators said, infringes on gun owners’ rights, and the change would help make gun restrictions more consistent.

Interior officials say the new rule is an effort to modernize one that was established to prevent poaching. That rule was last changed in 1982 when six states had “right-to-carry” laws that allow residents with permits to carry concealed weapons. Forty-eight states now have such laws.

The new rule would apply the weapons laws of states bordering a park or refuge. Gun owners would be allowed to carry concealed weapons in national parks and monuments in states where they may carry such weapons in state parks and state wildlife refuges. Twenty-four states have such laws.

“It’s an effort to recognize the concept of concealed carry and to be able to defer to states and state authority,” Mr. Paolino said.

State gun laws govern both of the other large federal landlords, the United States Forest Service and the Bureau of Land Management, he said.

Image Antlers and skulls of illegally killed animals. Credit... Anne Sherwood for The New York Times

But in the case of a large national park like Yellowstone that is bordered by three states, Idaho, Montana and Wyoming, it was not clear which state’s laws would apply.