The odds of claiming this week's bonanza US lottery prize are less than one-in-300-million -- but one "lucky" convenience store outside Los Angeles is already counting its winnings.

A sign above the counter of the otherwise unassuming shop in California's Chino Hills proclaims itself the "LUCKIEST 7-ELEVEN IN THE WORLD," six years after it sold a winning ticket for the largest jackpot in US lottery history.

With the nationwide Mega Millions prize now exceeding $1 billion once again, customers from far and wide were lining up Thursday, hoping that lightning will strike twice.

"This is the lucky store, so I'm hoping it becomes lucky for me as well," said Vish Josai.

The current prize for Friday evening's draw stands at $1.02 billion.

Back in January 2016, a winning ticket was purchased at the store by a customer who shared the roughly $1.6 billion with two other lucky people who had also picked the correct six numbers elsewhere in the country.

For store owner Balbir Atwal, who has owned the store for almost three decades, the 2016 win marked a turning point.

Now, "anytime the jackpot goes high, a lot of my neighbors come" to buy tickets, said Atwal.

"Even people from other cities come here -- people come even from Las Vegas to play here."

"A lot of people travel to Disneyland, and they (also) come here just to see this place," he added, referring to the giant amusement park and resort just 20 miles (32 kilometers) away from his store.

Customers who have come specifically to buy lottery tickets usually end up buying other goods, too, boosting his profits.

Still, despite his shop's track record in doling out mega-prizes, the digital sign displaying the current jackpot does not have enough numbers to cope.

It remains "stuck" on $999 million.