An unexpected increase in tourism to a small town could be a bonanza for the locals. Bonanza means "a sudden opportunity to make money."
Bonanza is a noun that means "a sudden rush of wealth or good fortune," but in a more scientific sense it means "a rich source of a precious metal." So, if you happen to strike gold in your backyard, that would be a bonanza on both fronts. "Boom towns" that sprung up during the California Gold Rush were created by a bonanza. More casually, bonanza can mean something like "a big to-do," or an extravaganza.