Northern United States
If you're looking not for a short weekend getaway, but for a month- or months-long adventure, consider a 3,262-mile (5,249.7-kilometer) trip from Bangor, Maine, to Seattle, Wash., across the northern United States. The map is easy: Almost the entire trip is on I-90 (in the west) or I-84 (in the east). Don't forget to pack your passport, because after tagging the Big Apple, the best route takes you up through the Adirondacks and into Canada via Niagara Falls. Jump back into the states in Pennsylvania, then find your inner long-distance trucker as you zip on interstates through Illinois, Wisconsin and Minnesota.
Eventually, in Wyoming, you reach the country's backbone -- the Continental Divide near where Lewis and Clark found themselves blocked by a fierce winter and ate their tallow candles. Continue through Yellowstone National Park and Idaho, and eventually make the long, slow descent into Washington State.
Like any road trip, and especially any long road trip, don't forget to take your time and check out some side roads. If you spend your whole trip on I-90 and I-84, you'll miss the city lights and country landscapes along the way.