through the NRA you can get a book called the "Travelers Guide to Firearms Laws of The Fifty States". I have the 2003 issue but things may have changed but according to it Maryland does not recognize any other CCW's and to carry a handgun it must be securely cased and unloaded outside of the passenger compartment, so either in the trunk or bed of your truck. At the time of this publication SC recognizes CCW's from Arkansas, Tennessee, Utah and Wyoming. In SC you can carry a loaded handgun in your glove box, cosole or trunk but not in the open. Like I said this is from 2003 and there is a new edition available and I would strongly suggest getting a copy and even then contact local authorities to confirm because things change so fast and as they say ignorance is no excuse and I know of a couple people that have gotten themselves into deep sh*t over stuff like this. The book has alot of other good info too and what I gave you is just the bare bones bottom line so I think it's something anyone that owns a gun should have a copy of.