S.C. Code Ann. § 5-7-155: Police jurisdiction over certain streets and highways along which municipal boundaries run.

If any portion of a street or highway is within the boundary of a municipality, the right of way of the street or highway not within the municipal boundary but touching the boundary is nevertheless considered to be within the boundary of that municipality for purposes of its police jurisdiction.

A street or highway which serves as the boundary between municipalities is under the police jurisdiction of both municipalities regardless of the municipality in which the street or highway is located.