Mammoth Cave National Park in Kentucky and Saguaro National Park in Arizona will now allow mountain biking on some existing and future trails.

On Oct. 12, Mammoth Cave granted mountain bikers access to the Mammoth Cave Railroad Bike and Hike Trail and the White Oak Trail. They will also be able to use the planned Connector Trail near Maple Springs and the Big Hollow Trail north of the Green River.

Mountain Bikers in Saguaro National Park will be able to use the three-mile Hope Camp Trail beginning on Dec. 1, 2012. The path connects Tuscon, AZ to the Arizona Trail.

The decisions are part of a growing trend to allow mountain bikers to use trails within national parks, recently made possible by a NPS regulation that gave individual park superintendents the power to allow bicycles on new roads and pathways, according to the New York Times. The goal of the regulation is to promote a healthy way to explore national park areas where motor vehicles are not allowed. 

Everglades National Park, Grand Canyon National Park, Hawai'i Volcanoes National Park and Olympic National Park are some of the other locations where trails have opened up to mountain bikers.

Via IMBA.