Not sure exactly what you are looking for (your intended use would better help with suggestions).
For raw "elevation" data nothing beats the
USGS Topographical maps. These are exceedingly detailed.
Google Earth may be another resource for you. Run your cursor along a highway and see it's elevation and layout.
If getting the lowdown on hills are your concern then the
Mountain Directory West for Truckers, RV, and Motorhome Drivers (Paperback) and the one for the
east are you best bets. Amazon links given, other sources for them are available too.