I've lived in the same town in Pennsylvania since I was a child. The house I grew up in sat directly behind a railroad track. It was part of the Reading Railroad line (yes, the same Reading Railroad from the Monopoly game). I can remember waking up in the middle of the night to a train roaring and shaking our house.
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Now, as an adult, that same railroad track has been converted into a community trail for walking, jogging, biking and dog walking thanks to the Rails-to-Trails Conservancy (RTC). The RTC works with local communities to map multi-use trails out of obsolete railroads.
The trail in our area (known as the Rail Trail) is 1.75 miles long. When weather permits, I walk the rail trail from one end to the other and back for a healthy 3.5 mile walk at least three times per week. Over the past few years it's become my therapy. Forget shrinks and yoga, just give me an mp3 player and a pair of sneakers and all my troubles melt away.
For information on trails in your area, visit www.traillink.com .