I cross the Savannah River from Georgia on the old GA25 bridge near Wentworth and continue to US17 and about 8 miles north to Hardeeville. This stretch of 17 is a shoulderless parkway but not too bad off-rush-hour. From Hardeeville (good, cheap motels) continue north on 17. There is little traffic as it parallels I95. After Ridgeland 17 becomes one with the interstate but the frontage road is off to the left just before the interchange. Follow this about 10 miles to the interchange where 17 goes east. Continue on 17 to Alt 17. Take this north to Walterboro. KOA at Yemassee. From Walterboro go a few miles east to Sidneys Road just past the airport. Go north on Sidneys Rd. to SC61.
Take 61 east to 17 near Charleston. It is somewhat congested as you approach 17 but cycleable. Then go east on 17. Pick your way through the city (mostly poor residential but not dangerous) to the Arthur Ravenal Bridge with its superb bike/hiker trail. At the end of the bridge turn right on 703/Alt17 to avoid the bad stretch of 17 through Mount Pleasant and go to Rifle Range Road on your left. Go NE on Rifle Range Rd. to Porcher's Bluff Road, turn left and go on to Morgan's Point Road. This goes right by a KOA and on a few miles, paralleling 17. Eventually you have to go left and onto 17 but by then there is cycleable shoulder. Just continue on 17 to Myrtle Beach and North Carolina.