Although recent sightings have occured, almost all of the encounters and stories of the Jersey Devil come from the 1800-1900's. It all started shortly after the birth of the devil, of course all of  the encounters happening in regions of New Jersey. The story of the devil had spread all across the pine barrens, and men, women, and children were all too frightened of the beast to even go out at night. around 1740 the pine barrens residents asked a local minister to give the devil an exorcism, but the man said that it would take up to 100 years. In 1840 the devil returned to the region snatching sheep and small dogs, even sometimes children, and people all around were locking their doors and hanging lamps outside as to keep the monster away. One of the most known sightings of the Jersey Devil is in 1909 when thousands of people witnessed the devil or his footprints, causing schools to shut down and factories close. Time after time again, endless accounts of the devil being seen, people were terrified of the devil from his encounters with town folk. That same year, the Philadelphia zoo offered ten thousand dollars to anyone who could capture the Jersey Devil, but no one would take up the offer. When the end of 1909 came around, the accounts of sightings started to wither away, and eventually, the jersey devil vanished. He was spotted a few more times in the next 100 years, but nothing as wild and disastrous as his visits in 1909.

sources:
 Perticaro, Anthony, "The Jersey Devil of Pine Barrens", http://www.strangemag.com/jerseydevil1.html
Taylor, Troy, "The Jersey Devil, Legend or Truth?", 2002, http://www.prairieghosts.com/jerseydevil.html