 Well, fireworks are sold at Delaware retailers and big billboards advertise retailers across state lines. But what are the rules surrounding fireworks in the first state? WDEL's Mark Fouser takes a look. The Delaware State Fire Marshal's Office says certain fireworks like sparklers, ground-based displays, and some other non-airborne, non-explosive novelty items can be used only on July 4th, the third day of Diwali, New Year's Eve, and New Year's Day. And that's it.