SIMPSONVILLE, S.C. — A flimsy piece of paper that crossed the counter of a convenience store on a country road in South Carolina is now worth $1.537 billion, so lottery officials could hardly be blamed Wednesday if anxiety tinged their excitement.

They said a single ticket sold at the KC Mart in Simpsonville matched all six numbers to win the Mega Millions jackpot. And unless the winner chooses to come forward, the world may never know who won.

“Our message to the $1.5 BILLION#MegaMillions jackpot winner: Sign the back of the ticket, place the ticket in a safe location, speak with a trusted advisor and CALL THE LOTTERY at 1-866-736-9819. Take a deep breath and enjoy the moment!” the South Carolina Education Lottery tweeted.

The prize is extraordinary by any measure, but particularly so for South Carolina, where it would be enough, if the winner was so generously inclined, to shower roughly $307 on each of the state’s 5 million people. It’s about as much as 20 percent of the $8 billion that state lawmakers have to spend each year.

An earlier Mega Millions estimate of $1.6 billion would have been a world record for lotteries, but sales came in below the $1.586 billion Powerball jackpot prize shared by winners in California, Florida and Tennessee in January of 2016.

“The final total was less than the $1.6 billion estimate,” said Carol Gentry, a spokeswoman for the Maryland Lottery, which leads a consortium of state lotteries participating in the Mega Millions jackpot.

“Estimates are based on historical patterns,” she explained Wednesday in a phone interview. “Typically, about 70 percent of sales occur on the drawing day, so forecasting precise numbers in advance can be difficult. That’s why we always use the term estimate.”

The ticket is worth about $877.8 million in a lump-sum cash payment, which most winners choose to take, rather than collect the full amount in annual payments over three decades.

South Carolina is one of eight states — along with Delaware, Georgia, Kansas, Maryland, North Dakota, Ohio and Texas — where winners can remain anonymous. The winner has up to 180 days to claim the prize.

Holli Armstrong, a state lottery spokeswoman, said the retailer will get a $50,000 payout. TV trucks and gawkers flooded the parking lot ahead of a news conference at the KC Mart and Exxon station, which sits at the bend of a road where Greenville’s suburban sprawl gives way to farm fields.

The winning numbers were 5, 28, 62, 65, 70 and Mega Ball 5.

Mega Millions is played in 44 states as well as Washington, D.C., and the U.S. Virgin Islands.