Some sort of explosives, believed to date to the 1930s, have been found in Sequoia National Park's Crystal Cave. The discovery has prompted the cave's closure and evacuation while the National Park Service's regional chief blaster assesses the situation.

A gray wolf has been illegally shot and killed just outside Grand Teton National Park. Wyoming wildlife officials have posted a $3,000 reward for information leading to the arrest of the poacher.

With hazing operations resuming to drive bison back into Yellowstone National Park, conservation groups are urging Montana Governor Brian Schweitzer to "provide leadership" to resolve the controversy.

May is a month that looms large in the annals of the Civil War. Battles fought in northern Virginia during that month had major implications for the war’s outcome. Today, visitors can walk the hallowed ground of Fredericksburg and Spotsylvania National Military Park and reflect on the deeper meaning of the pivotal events, gallant deeds, and unspeakable suffering that took place there nearly a century and a half ago.