California and New York are often cited as key examples of states with successful restaurant grading systems, but South Carolina was actually the first state to enact statewide grading requirements in 1995. In general, restaurants are inspected by the state or city health department and graded with an A, B, or C, enabling consumers to make wise choices about the sanitation of restaurants they choose to eat in:

• A - the restaurant is clean, up to code, and free of violations.
• B - it has some minor sanitary issues that need to be fixed.
• C - the restaurant has significant issues and is at risk of being closed. 

While states vary on requirements for posting of the grade, many require that the restaurant post signage in a location visible from outside the establishment, and some post the ratings online as well. There also are various independent online lists and apps by which consumers can check out the ratings of their local restaurants before leaving home. 

The systems seem to be working for the cities and states which enact them, as a 2017 report from the New York City Health Department, which enacted a ratings law in 2010, showed that:

•  With 93% of its restaurants earning an A rating, sanitary violations and salmonella cases had significantly decreased.
  • Salmonella rates fell 32% since 2010.
  • There was a 41% drop in sanitary violations from the 2012 peak.