A flimsy little piece of paper that crossed the counter of a convenience store on a country road in South Carolina is now worth $1.537 billion US, so lottery officials could hardly be blamed Wednesday if their excitement seemed coloured by anxiety.

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

Our message to the $1.5 BILLION <a href="https://twitter.com/hashtag/Mega?src=hash&ref_src=twsrc%5Etfw">#Mega</a> Millions 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.<br>Take a deep breath and enjoy the moment! —@sclottery

An earlier Mega Millions estimate of $1.6 billion would have been a world record for lotteries, but actual 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," confirmed Carol Gentry, a spokesperson 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 morning in a phone interview with The Associated Press.

Jackpot had been growing since July

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.

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

It's possible that the world will never know the winner. South Carolina is one of eight states — along with Delaware, Georgia, Kansas, Maryland, North Dakota, Ohio and Texas — where winners can remain anonymous.

The jackpot had been growing since July, when a group of California office workers won $543 million.

The largest-ever U.S. lottery prize, a Powerball jackpot worth $1.586 billion, was split between three winning tickets sold in California, Florida and Tennessee in January 2016.

Worsening odds

The lucky player overcame miserable odds. The chance of matching all six numbers and winning the top prize is 1 in 302.5 million.

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

It will likely be days or even weeks before a winner steps forward to claim the prize.

People line up in the hallway of a midtown New York City office building to buy Mega Millions tickets on Friday. (Timothy A. Clary/AFP/Getty Images)

Lottery officials and financial managers encourage people to take time to map out a strategy for investing their hundreds of millions of dollars, and winners must deal with security concerns befitting someone who suddenly is immensely wealthy. Depending on the state, winners have from 180 days to a year to claim their prize.

Although Tuesday's jackpot was extraordinarily large, it's no fluke. It reflects a trend toward ever-growing lottery prizes due to changes in the game that worsened the odds with hopes that bigger jackpots would result in better sales.

Officials with the Powerball game were the first to make that move in October 2015 when changing the odds of winning the jackpot from 1 in 175 million to 1 in 292.2 million. Mega Millions followed suit in October 2017, resulting in the odds worsening from 1 in 259 million to 1 in 302.5 million.

While most attention has been on the Mega Millions game, Powerball also has been soaring. The estimated prize for Powerball's annuity option in Wednesday night's drawing is $620 million, with a cash prize of $354.3 million.