What year did they change the blue laws?

I wasn't sure either so I found the following two articles.

TRAVEL ADVISORY; Sunday Drinks In Myrtle Beach

Published: December 8, 1991

Tourists can now get a drink on Sundays in Myrtle Beach, S.C.
A measure permitting Sunday liquor sales in bars and restaurants was approved by voters on Election Day. Elsewhere in South Carolina, alcohol sales are prohibited from midnight Saturday until 6 A.M. Monday, unless a county or municipality agrees to allow the purchase of a special $150-a-week license.
Opponents argued that the change would undermine Myrtle Beach's reputation as a "family beach," but a 68 percent majority of voters approved the measure Nov. 5, allowing sales to begin that weekend. Groceries, liquor stores and convenience marts are still prohibited from selling alcohol on Sunday.

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Sunday Beer Sales Begin in S.C.

Jul 21, 2003

MYRTLE BEACH, S.C. -- Beer and wine went on sale at some convenience stores in Horry and Georgetown County on Sunday. They will likely be joined by more than 100 convenience stores next weekend, reports The (S.C.) Sun News.

The S.C. Department of Revenue mailed out permits last week to stores seeking to sell beer and wine on Sundays. But most stores had not yet received the permits, and would not sell beer and wine for another week. Only a handful of stores were selling beer and wine Sunday , including most Pantry locations in Murrells Inlet and Pawleys Island, BP Amoco in Pawleys Island and a Kangaroo convenience store in Georgetown. About 100 stores in Horry County and 40 in Georgetown have so far applied for permits, according to Danny Brazell, spokesman for the Department of Revenue. More are expected.

"The applications are stacking up," Brazell said. "It's getting hard to keep track of them."

The Pantry Inc., Sanford, N.C., aggressively went after the permits. Fifty have been awarded in Horry County alone, the report said.

The state ruled in June that businesses such as convenience stores and groceries in more than a dozen counties could sell beer and wine on Sundays because they had approved referenda since 1993 authorizing the Sunday sale of alcohol in restaurants and bars. The change has met with little public opposition. But one Pantry employee said he doesn't like that his store is able to sell beer and wine on Sundays now that it has a permit.

"It's Sunday. It's something that should be respected," said Jason Gains, a cashier at a Murrells Inlet Pantry. "There was nothing wrong with the rules. It was the one day of the week when you didn't have to worry about some drunk on the road."