If you're asking about driving advice for such a distance, I have some tips (being that I used to drive 24+ hours straight between uni and home).
Find your "sweet spot" regarding the amount of time between driving and having some sort of a break. For myself, every three hours I'd find a gas station+rest stop, top off the tank, do the restroom goodness, and have a little walk. Bypass lots of coffee/energy drinks, as though they are yummy, over such a long haul they will turn your stomach (and your butt) into a hate machine.
Some people can drive 20+ hours and still be a little sane. It may sound silly, but if you're driving such a period of time without sleep, and excess caffeine, you may see weird things: taillights looking like faces, bushes on the road-side looking like children, etc. I've seen all these things and more, when driving such hauls, and it makes it rather unsafe. Should you feel out of your element, find a rest stop, and grab a nap pronto. Also too much caffeine and then a nap will make you crash (not your car, but maybe), and you'll look like a fool as you're driving in a shivering, chattering, shaking mess. You'll look dumb, and it's not safe. Don't do it.
Have good tunes. Lots of good tunes; singing tunes.
It's been mentioned already, but take your time with the trip. If you see a sign for Largest X In The State, go have a peek. All kinds of memorials and oddities you'll find just by driving interstates.
Your newfangled devices like GPS are nice and all, but learn how to read a road atlas (map). When you start getting into the mountains and valleys, such services can be spotty. So take a moment to know what interstate you'll be driving for 40 hours.
Speaking of interstates: bypass Chicago by all means necessary. Also Joliet. Traffic if those areas is a nightmare, and the drivers are stupid. On a map, if may take you longer in miles to go around, but the headache, hassle, and stress you'll save is worth it. This rule applies for pretty much any large city, especially if you're driving through during peak times (avoid doing this).
Adding onto that, your most likely interstate (which I suggest you keep to, they're well maintained) will be I-90. It's what I took when driving from Illinois to New Hampshire, and it's a Seattle to Boston route. Quite literally runs from one side of the country to the other, and you can't get lost. Eastern side of the country, I-90 has good facilities (or did when I drove it), and the road maintenance was quality.
Turn to Side B for Life Advice.