Tonight and tomorrow, lottery players will get to gamble for an uncommon prize: a half-billion dollars, split between the Powerball and Mega Millions games.

But to wager on both, you'll have to do some driving.

Powerball - played in Pennsylvania, Delaware and 27 other states - has seen its jackpot rise to its fourth-highest total ever, $300 million. The drawing is tomorrow night.

Mega Millions, played in New Jersey and 11 other states, has $201 million on the line tonight.

"Everyone is very excited. Maybe too much," said Sam Ahmed, owner of the Corner News kiosk at the Cherry Hill Mall. He sold 3,000 tickets Wednesday, and expected yesterday's sales to jump to 5,000 or more.

In Delaware County, at the Concord Pharmacy in Glen Mills, cashier A.J. Wood reported that many of yesterday's lottery customers were first-timers.

"They come in and say, 'What's the big one and how do I do it?' " Wood said.

Veteran players showed up, as well, undaunted by the 1 in 146.1 million odds.

"I look at it as entertainment," said Carolan Appleteon, 60, of Glen Mills.

If no one wins tomorrow, Powerball could top its record prize, the $365 million won by eight coworkers from a Nebraska food-processing plant in February 2006.

They declined to take their winnings paid out over decades, instead splitting $177 million in cash.

The current $300 million Powerball would pay about $140 million if the winner, or winners, took the immediate payout.

Jackpots grow rapidly for many reasons.

Regulars buy more tickets, infrequent customers open up their wallets on a lark, and friends at work are more likely to form pools.

At the Payal News stand at 11th and Market Streets, a woman named Maureen handed over an envelope stuffed with $115.

"Everybody at the office daydreams," she said.

Don't forget the role of media hype in boosting jackpots, said Gail Howard, author of The Lottery Master Guide. When New York's first $5 million jackpot made headlines, lines at the local convenience store wrapped around the block, she recalled. Today, a jackpot "has to be close to $200 million before there's really any interest," she said.

"When the media hypes it, that's when everybody thinks, 'I'm going to be left out. I better get my ticket, too.' . . . It's the herding instinct."

Hear those galloping hooves?

Take the record Mega Millions jackpot earlier this year. Nine weeks were needed without a winner to reach $100 million. Five more drawings and the jackpot hit $216 million.

The very next jackpot: $275 million.

Four days later: $390 million.

Powerball could be poised for a similar breakthrough. But a few things work against that.

More people live in the 12 Mega Millions states than in Powerball's 29, so there are more people available to bet, thereby increasing the potential win.

"Look at the states you're talking about: New York, California, Michigan, Illinois, Texas. . . . They're all pretty large states," said Dominick DeMarco, a spokesman for the New Jersey Lottery.

Mega Millions has longer odds - about 1 chance in 176 million of winning with a single ticket - so it's more likely not to have a winner and roll over.

Finally, Powerball has a cap and Mega Millions doesn't.

Once Powerball sets a new record, the next jackpot can increase by only $25 million, explained Stephanie Weyant, press secretary for the Pennsylvania Department of Revenue. The extra money wagered gets funneled into secondary prizes.

Still, records could be in reach. Suppose there's no winner tomorrow, and Powerball surpasses its previous high of $365 million. Then a Wednesday rollover would add $25 million more for a new U.S. record.

Assuming Mega Millions doesn't outpace it.

Yesterday at a 7-Eleven in Haddonfield, customers were lining up during lunch hour to buy fistfuls of tickets.

Linda Polidaro of Collingswood, who works for a large Westmont law firm, bought 26 for her office pool.

"We always play when the jackpot gets big," she said.

And if she wins?

"First, we're gonna split the money - then, I'll buy a new house, a new car and take care of my daughters. Then maybe I'll buy an awesome dental lab for my husband. The rest I'll give to a children's shelter."

In Center City, at the bluntly named News Stand in the basement of the Gallery mall, Evelyn Turrentine, 79, bought her one Powerball ticket.

"If I win, I'm going to give Jesus Christ the first 10 percent and the rest I'm going to spend," she said gleefully.

Contact staff writer Peter Mucha at 215-854-4342 or pmucha@phillynews.com.
Inquirer staff writers Bob Moran, Sam Wood and Kathy Brady Shea contributed to this article.