In south Carolina, right after prohibition up until a few decades ago, you were not allowed to advertise any signs (taller than 3 inches) on a liquor store that

In south Carolina, right after prohibition up until a few decades ago, you were not allowed to advertise any signs (taller than 3 inches) on a liquor store that indicated you were a liquor store. So they marked themselves with big red circular dots instead (starting around 1940s). The laws have since relaxed but many liquor store still use the red dot and are often referred to as "red dot stores"