The Yough Bike/Hike Trail in Ohiopyle is part of the Great Allegheny Passage trail system that runs from McKeesport to Cumberland. In Cumberland you can pick up the C&O Canal Trail to Washington, DC. Check out the details at these great sites:

http://http://www.dcnr.state.pa.us/stateparks/parks/ohiopyle.aspx
www.youghrivertrail.com
www.atatrail.org
www.GAPtrail.org,
www.trailtowns.org