Google bike map from Philly to Washington better in my opinion, ACA kind of outdated and for some reason, avoids the NCR trail which would not only shorten the distance on the ACA map, but give you a fairly flat ride. The ACA map seems to add a ton of mileage also.

Also you can ride PA route S to York, then catch the York County/NCR trail all the way to the Baltimore suburbs, then use Maryland's bike map to take you into DC. Hopefully in a few years, the WB&A trail system should make going from Baltimore to Washington easier when it is complete.

Maryland makes an excellent bicycle route map that you can view online for order for free off the internet.

Sites: PA bike map - http://www.bikepa.com/routes/index.htm
MD bike map - http://www.mdot.maryland.gov/Office_...ycle_Maps.html