hitching or driving to alaska

You need a passport, clean criminal / arrest record (they won't let me in for charges I was found innocent of) and proof that you have at least $300 to your name (this changes sometimes depending on the customs office, could be more or less). Its normally a good idea to tell them you have someone to stay with once you're in canada. Overall they ain't too happy about hitchers, but if you meet these requirements you'll most likely make it through.
 
I guess I should've mentioned that I'm only talking from personal experience and the experiences of friends who cross regulary. That said I would still try to have all the things I've mentioned. I've known plenty of people who've been turned around for not having enough cash and / or for having no contacts in canada. The last time I tried I was told that anyone with my # of felony arrests (4) would be rejected at any crossing, despite the fact that I have no felony convictons.