S.C. Code § 4-9-90
Council members must be elected from defined single-member election districts unless otherwise determined under the provisions of subsection (a), (b), or (c) of Section 4-9-10 or under the provisions of any plan ordered by a court of competent jurisdiction prior to May 1, 1986. In the event the members of the governing body are required to be elected from defined single-member election districts, they must be elected by the qualified electors of the district in which they reside. All districts must be reapportioned as to population by the county council within a reasonable time prior to the next scheduled general election which follows the adoption by the State of each federal decennial census. The population variance between defined election districts shall not exceed ten percent.
Members of the governing body of the county shall be elected in the general election for terms of two years or four years as the General Assembly may determine for each county commencing on the second of January next following their election. Vacancies on the governing body shall be filled in the manner of original election for the unexpired terms in the next general election after the vacancy occurs or by special election if the vacancy occurs one hundred eighty days or more prior to the next general election.
In those counties where the members are elected for four year terms, such terms shall be staggered. If necessary, in the initial election for members one-half plus one of the members elected who receive the highest number of votes shall serve terms of four years and the remaining members elected shall initially serve terms of two years only. In those counties in which the chairman of the governing body was elected at large as a separate office prior to the adoption of one of the alternate forms of government provided for in this chapter, the chairman shall continue to be so elected.
In any county in which terms of county council members are for two years only, the council may by ordinance change such terms to four-year staggered terms but such ordinance shall not become effective until approved by a favorable vote of the qualified electors of the county voting in a referendum conducted for that purpose. In the event the referendum is conducted at the time of the general election in which council members are elected, and the vote is favorable on the ordinance, the terms of council members shall automatically be changed to four-year terms except that of those elected in that general election one half plus one of such members who receive the highest vote shall serve four-year terms and the remaining members elected shall serve terms of two years only.
Any council member who is serving a four-year term in a district that has been reapportioned and whose term does not expire until two years after reapportionment becomes effective shall be allowed to continue to serve the balance of his unexpired term representing the people in the new reapportioned district if he is an elector in such reapportioned district. In the event that two or more council members, because of reapportionment, become electors in the same district, an election shall then be required. Provided, however, that if any seat should become vacant after election districts have been reapportioned but prior to the expiration of the incumbent's term of office due to death, resignation, removal, or any other cause, the resulting vacancy shall be filled under the new reapportionment plan in the manner provided by law for the district that has the same district number as the district from which the council member whose office is vacant was elected. For the purpose of this section, a council member will be deemed a resident of the district he represents as long as he resides in any part of the district as constituted at the time of his election.
S.C. Code § 4-9-90