I am helping to move my girlfriend from Portland to Philadelphia starting around January 19. We have a maximum of nine days to make the trip. (We don't want to kill ourselves driving non-stop.) We will probably be driving a rental truck for all her stuff.
Should we definitely avoid the more direct, northerly route, or take our chances?
Are you comfortable in snow?
My bet would be on the northern route unless you are uncomfortable driving in snow. The heaviest snows of the winter rarely hit until the middle of January and early Feb in the rockies and western plains. The 19th is pushing it, but that route is so beautiful!
If the roads are reasonably dry and clear you can make the distance in an easy four days. So nine sounds pretty safe to me.
If you go south -- remember that the ice storms in Texas can be really bad! I would take a blizzard on I-80 in Wyoming anytime over ice storms on I-40!