"Holy cow," said Mayor Janice Curtis, who first learned of her city's new prominence after receiving a call from the Washington Post. "I think it's wonderful news."
The winning numbers were 5-28-62-65-70, with a Mega Ball number of 5, and lottery officials estimated that 75 per cent of all number combinations had been purchased by the time of yesterday's drawing. The estimated cash option - should the winner choose to take a one-time lump-sum payment instead of annual payouts over 30 years - is US$878 million before taxes, according to Mega Millions officials.
The six winning numbers were printed on a ticket sold at the store off Lee Vaughn Road, about a 6.5km drive from city hall. It is a rural area of a rural town outside Greenville, where Curtis said "there's a church on every corner."
When it comes to the KC Mart, that is accurate. The store is flanked by the Clear Spring Baptist Church and the New Pilgrim Baptist Church nearby.
Lottery officials have not announced the identities of a winner or winners. The impact on their lives is still unknown. So is the newfound prominence of Simpsonville.
"This could be a good and bad thing," she said. "It could put us on the map."
Lottery officials had said for days that the jackpot would be worth an estimated US$1.6 billion, a US lottery record.
But when the jackpot was finalised, it was downgraded to US$1.537 billion. So the lottery record remains US$1.586 billion, for a Powerball jackpot shared by three winning tickets in January 2016.
"The final total was less than the US$1.6 billion estimate because estimates are based on historical patterns of jackpot rolls, but there are few precedents for a jackpot this size," said Seth Elkin, a spokesman for Maryland Lottery and Gaming, which heads the Mega Millions Group.
"Typically, about 70 per cent of sales occur on the drawing day, so forecasting precise numbers in advance can be difficult," he said.
South Carolina Education Lottery spokeswoman Holli Armstrong said the drawing was the state's first Mega Millions jackpot win. Five years earlier, a Powerball player in the state won a US$399 million jackpot; the man who claimed that prize remained anonymous. (His dog was the first to learn the news, the AP reported at the time.)
How the residents of Simpsonville manage the new attention could depend if the winner decides to be publicly identified.
South Carolina is one of just a handful of states that allows lottery jackpot winners to remain anonymous. The state encourages players to sign their tickets upon purchase, but that may prove problematic if anonymity is desired by the winner or winners.
The winner has 180 days to claim the prize, Armstrong said.
