Asbury Park
Asbury Park is technically neither abandoned nor a town, but it's close enough to warrant a mention here. It was one of the country's earliest amusement parks and included quarters for the park staff. According to all accounts, the park closed because they were unable to keep vagrants and bikers outside the park gates at night, and the park was eventually overrun.
Most of the original rides have been sold, but the buildings still stand in all their creepy carnival glory - everything from the facade for a freak show to a warehouse-like building with a huge clown head engulfing the entryway. It's almost enough to make you hear carousel music. While Asbury Park is one of the more modern abandoned complexes in New Jersey, it still feels historic. Luckily, the fear of mad biker gangs has kept the place from being torn down completely.
I personally doubt the vagrant explanation on Asbury Park. Even though there are several modern camp sites in and around the park, I think it was more likely the park closed due to financial hardship. Just as resource-shift is the leading killer of cities, overspending and undercharging is the number one killer of amusement parks.