I agree with Taranwanderer & nineback. take the extra time and go I-81. the traffic & tolls from Philly to DC are horrible at any time of day. The tolls for a car would be about $30 alone, probably doubled with a trailer, or more...
and I personally cant stand the boring scenery through VA & nothing but pine trees in the Carolinas.
I-81 is hilly but much better scenery, CHEAPER, and lot less stressful.
Jim & Evelyn
-2015 Ford F-350 XLT Dually
-2014 XLR Hyperlite 27HFS
-2012 Harley Davidson Street Glide (his)
-2004 Harley Davidson Fatboy (hers)