It shall be unlawful for any railroad or Pullman car company doing business in this State to collect from any person within the boundaries of the State any surtax or surcharge for Pullman car transportation from one point to any other point within the bounds of the State. But nothing in this section shall be construed to affect in any way the charge which any railroad or Pullman car company requires for transportation in interstate travel.
S.C. Code § 58-17-1940