Powerball took another major upward bounce, landing at $600 million, the biggest Powerball jackpot ever.

The cash payout is $376.9 million, second to the Powerball record of $384.7 million set in November.

The record for any U.S. lottery was set by Mega Millions in March 2012, and that could also fall. That jackpot wound up with an annuity worth $656 million, $471 million for the cash.

See "Largest jackpots in U.S. lottery history."

"This is uncharted territory," said Chuck Strutt, who oversees Powerball as the director of the Multi-State Lottery Association. "... We are being conservative with the estimate."

Since the run began in early April, more than 386 million tickets have been sold, a take of more than $772 million, Strutt said.

"We expect to sell $540 million for Saturday alone, pushing sales to $1.3 billion for the entire run," he said.

After Wednesday night, when a $360 million jackpot rolled over, the jackpot was originally announced as $475 million, but quickly rose to $550 million on Thursday.

Even with all the frenzy, it's possible the jackpot could roll over again.

"Based on our current estimate of sales, we expect an 80 percent chance of a jackpot win," said Strutt.

That's 1 chance in 5 that no one will win Saturday night.

If that happens, all bets are off as to how high the jackpot might go.

If it can rise $240 million in just two days, the first billion-dollar jackpot is far from unthinkable. Instead of three days, players will have four -- Saturday to Wednesday -- to buy tickets for an even more beguiling prize.

The odds of winning won't change. They're lousy: 1 chance in 175 million with a single ticket.

Lurking is another big Mega Millions jackpot, worth $190 million tonight.

If that rolls over, surely rising well over $200 million, and if Powerball gets hit, the excitement could shift to Mega Millions, fueling another mind-boggling amount.