Since 1986, national park visitors across the country have turned to the Passport To Your National Parks program to preserve cherished memories of their park travels by collecting ink cancellations at every national park they visit. This year the program is celebrating its 35th birthday. For 35 years, the Passport to Your National Parks program has assisted visitors explore and protect the vast natural, cultural, and historic treasures of America.

The world's longest cave, protected as Mammoth Cave National Park in Kentucky, is longer than you might have thought. Recent efforts by the Cave Research Foundation have mapped eight more miles for the cave, bringing its currently accepted length to 420 miles.

You no longer need to travel to Death Valley National Park to find out how hot it is at Badwater. Now you can check the latest weather conditions for the lowest point in North America from the comfort of your home.

Guadalupe Mountains National Park is moving its campground reservations system online to recreation.gov.