Nonprofit

Ohio River Water Trail

Ohio, Pennsylvania, West Virginia

Water Trail (other)

City, Town, or County

Ohio River Water Trail, Parkersburg WV

Ohio, West Virginia

National Water Trail

State

Oil Creek State Park Multi-Use Trail

Pennsylvania

Frontcountry Trail, Rail Trail

U.S. Fish and Wildlife Service

Okefenokee Wilderness Canoe Trail System

Georgia

National Water Trail

USDA Forest Service

Old Baldy Super Loop

Arizona

State

Old Erie Canal State Park

New York

Backcountry Trail

Bureau of Land Management

Old Growth Ridge

Oregon

Backcountry Trail

U.S. Corps of Engineers

Old Hickory Trail

Tennessee

Backcountry Trail, Frontcountry Trail

State

Old Highway 131 Trail

Wisconsin

Frontcountry Trail

State

Old Oak Trail

North Dakota

Backcountry Trail

U.S. Corps of Engineers

Old Post Road Mountain Bike Trail

Arkansas

Backcountry Trail

City, Town, or County

Olentangy-Scioto Trail

Ohio

Rail Trail

City, Town, or County

Orange Heritage Trail

New York

Rail Trail

Bureau of Land Management

Oregon High Desert Trail

Oregon

Backcountry Trail

Bureau of Land Management

Organ Mountain Trails - Baylor Pass Trail

New Mexico

Backcountry Trail

Bureau of Land Management

Organ Mountain Trails - Pine Tree Trail

New Mexico

Backcountry Trail

National Park Service

Otis Pike Wilderness Nature Trail (Burma Trace)

New York

Backcountry Trail

U.S. Fish and Wildlife Service

Ottawa Wildlife Interpretive Trail

Ohio

U.S. Corps of Engineers

Ouachita Geo-Float Trail

Arkansas

Water Trail (other)

USDA Forest Service

Ouachita Trail

Arkansas, Oklahoma

Backcountry Trail, Urban Trail