(FORTUNE Magazine) – Here's something city dwellers and suburbanites often have in common: abandoned railroad track beds that can be used for recreation. Example: the former Washington & Old Dominion route that runs 45 miles from Arlington, Virginia, to the Blue Ridge Mountains. An estimated two million people used the trail last year, including bicycling commuters like the one shown here. The Northern Virginia Regional Park Authority operates the trail, helped by more than $500,000 a year in licensing fees. AT&T, for example, pays $250,000 of that to run a fiber-optic cable underground. Interested? Contact the Rails-to-Trails Conservancy. The nonprofit group in Washington, D.C., has helped communities turn some 5,000 miles of old railroad beds into paths and walks. The outfit expects to celebrate the opening of the 500th such trail in October. There's more to come. In 1916 railroads operated 250,000 miles of cargo and passenger tracks. That's now down to 140,000 as the lines abandon between 3,000 and 4,000 miles a year. -- R.T.