In reference to roadways, US numbered highways are different from our Interstate highways. Most US# highways are suitable for rv travel and pass through picturesque parts of the country. But they also pass through towns so you will have slower traffic and traffic control lights and signs. As for the east coast area, around NY/NJ/CT, they have roads marked as parkways (pkwys). Stay off of these. They are marked as passenger cars only and clearances are very often low. If you use a gps system, set it on truck vs car when in this area to avoid parkways. You'd be surprised how many truckers make the wrong choice to enter these. US Route 30 runs west/east through our mid-section, coast to coast. I lived on it in Wyoming and now live only a mile from it in Pennsylvania. It also passes near Gettysburg, mentioned elsewhere. Good travels. Enjoy our country. I recently visited your area early in 2016(Vancouver).
