The alphamegalog of the cities of South Carolina lists the largest city in South Carolina for each letter of the alphabet. In this case, ‘largest’ is based on population within the city proper.

Aiken
Berea
Columbia
Dentsville
Easley
Florence
Greenville
Hilton Head Island
Irmo
Johnston
Kingstree
Lexington
Mount Pleasant
North Charleston
Orangeburg
Parker
Quinby
Rock Hill
Summerville
Taylors
Union
Valley Falls
Wade Hampton
(no X)
York
(no Z)