A Powerball ticket worth half a million dollars expires Thursday. Lottery spokeswoman Mary Neubauer says the ticket was purchased in March at a Kwik Star in Mason City.

“We’re at the last minute on this one and of course we’ve been reminding people during the six-month or 180-day period that they need to claim this prize, but we just haven’t heard anything yet,” Neubauer says. The ticket will be worthless once the lottery closes on Thursday. “The exact deadline for this is Thursday, September 12th at 4 p.m. This prize must be claimed at the lottery headquarters in Clive,” Neubauer says.

Neubauer says they tried everything they could to make people aware of the prize. “You know, we held an event in the store to raise awareness. Of course, we put out reminders over the months,” she says. “When we were in the store, it seemed like the people who came to us knew about the prize and had heard about it, and we were talking about it ourselves. So I think people can guess as well as I can what happened to the lot: Did someone just never check it and throw it away?”

This jackpot is a little unusual because it comes from what Powerball calls its “Double Play” option. “This option was just added to the Powerball game here in Iowa in November. And Double Play means that the numbers on your ticket are valid for two drawings on the night your ticket is valid for,” Neubauer says. “So they’re certainly valid for the Powerball drawing, but the Powerball Double Play drawing is about 20 minutes after the regular drawing.”

Neubauer said someone may have forgotten about the second drawing. “If you’re one of those people who think you had the ticket and threw it away or lost it, make sure you call us at the lottery before the deadline because we can put you in touch with our lottery security people,” she said. The $500,000 prize will go back into the Iowa Lottery prize pool if it isn’t claimed by Thursday’s deadline.