There are various versions of the story about the Jersey Devil. One was that Mrs. Shrouds of Leeds Point, New Jersey made a wish that if she ever had another child, she want it to be a devil and he was born misshapen and deformed. She sheltered him until one day his arms turned into wings and he flew away. Another was that a young woman fell in love with a British soldier during the Revolutionary war. She was eventually cursed by the people of Leeds Point and she gave birth to a devil. Some people believe the birth of the devil was punishment for the mistreatment of a minister by the Leeds folk.
Despite how the devil supposedly came into this world, there have been several eyewitnesses how swear they have personally seen the Jersey Devil. In the 19th century, a naval hero Commodore Stephen Decatur accidentally hit a flying creature while testing a canon. Former king of Spain Joseph Bonaparte spotted the creature while hunting. George Saarosy, a prominent business man, saw the devil at the New Jersey/New York border. Just to name a few.
Practically the only evidence there is that the devil exists is similarity in the story of how he was born, eyewitness testimonies, and footprints that are said to be his. The Jersey Devil has said to avoid man but not animals. Many people believe that the Jersey Devil could be the very essence of evil, embodied. It is said that the devil is an "uncanny harbinger of war" He tends to make himself known before conflicts and wars started, including the Civil War, WWI & II, Spanish American War and before the bombing of Pearl Harbor.
Many believe he is of a supernatural origin. When he was hit by the cannon ball, it seemed to actually just go through him and didn't really affect him any. He would also have to be about 260 years old now. Since he was seen in like 3 different states with in a week, he would have to be a pretty fast traveler.
Whether the Jersey Devil is real or not, the legend will continue to live on in whatever version. And there will be more sightings for as long as the legend is kept alive or possibly even longer. Who knows? There may really be something lurking in the woods in New Jersey.
More info: http://theshadowlands.net/jd.htm