With no jackpot winner in Friday night's Mega Millions drawing, the grand prize for the multi-state lottery game had swollen to an estimated $636 million on the day the numbers are pulled again.
Gary Miller, a spokesman for the Pennsylvania Lottery, said officials estimate that 65 percent of the possible number combinations for the game, which is available in 43 states, the District of Columbia and the U.S. Virgin Islands, will have been sold by 9:59 p.m. today, the cutoff for the 11 p.m. drawing.
"There's significant interest in this," said Mr. Miller, who added that since the present jackpot began accumulating in October, about 35 million tickets had been sold in Pennsylvania. As of Friday, the state's 9,100 retailers were selling about 7,000 tickets a minute.
On Monday, the Mega Millions money was the fourth-largest jackpot ever offered in North America, but with odds of winning it at about 1 in 259 million, another drawing without a jackpot winner is "certainly within the realm of possibility," Mr. Miller said.
Winners get the full amount (before taxes, of course) if they receive it in 30 annual payments. If they opt for a lump-sum payout, the prize falls to $316.5 million before taxes.
Mega Millions players pick six numbers from two separate ranges -- five different numbers from 1 to 75 and one number from 1 to 15. Though various combinations can win lesser prizes, to win the jackpot, all must match the balls selected at an Atlanta television station during the 11 p.m. drawing.
No one has won a jackpot since Mega Millions changed its rules in October, although there were nine $1 million winners in Friday's drawing, bringing the total to 39 since the new game was launched, Mega Millions said in a news release.
Among other tweaks, the starting jackpot went to $15 million from $12 million and a wider field of possible numbers -- 1 through 75 instead of 1 through 56 -- was introduced for the five "white ball" numbers.
The range for the single "gold ball" number decreased from 1 through 46 to 1 through 15. And while the odds of winning any prize went from 1 in 40 to 1 in 15, the odds of winning a jackpot went from 1 in 176 million to 1 in 259 million.
The rules changes were partly the result of customer surveys calling for bigger pots, said Paula Otto, executive director of the Virginia Lottery and lead director of the Mega Millions consortium.
"We have never had a jackpot over half a billion the week before Christmas. It's really exciting to be at holiday time with such a big jackpot," Ms. Otto said. By tonight, about 241 million tickets will have been sold nationwide since Friday's drawing, she added.
Without a winner tonight, the jackpot will likely surpass the $656 million prize split among three winning tickets in March 2012 and become the biggest in U.S. history.
If no one wins today, the jackpot is expected to grow to about $800 million by Friday, the next scheduled drawing, and could approach $1 billion by Christmas Eve. "The only time we know there's a winner is if 100 percent of the numbers are covered," Ms. Otto said. "We have had winners when only 10 percent of numbers are covered and roll-overs when 70 percent are covered. ... You never know. And that's part of the fun of the lottery."
Regardless of who claims the prize, Mr. Miller said Mega Millions has been a win for the Pennsylvania Lottery, which donates all of its proceeds to programs for the elderly.
Since the state joined Mega Millions in 2010, the game has generated about $187.4 million to that end. The current jackpot alone, which began building in October, has generated $16 million.
"In a very short period of time, this game has generated a lot of revenue," Mr. Miller said.
Correction (Posted Dec. 17, 2013) An earlier version of this story incorrectly stated the amount of money Mega Millions has raised in Pennsylvania for programs for the elderly.
Robert Zullo: email@example.com or 412-263-3909. First Published December 16, 2013 11:26 PM