I hich hiked from Santa Barbara to Homer via the Alcan Highway in 1983 almost 5000 miles. All of the above posts are true. I will add the following:
1) Bring a lot of 100% DEET.
2) Bring a mosquito proof tent otherwise you will never be able to sleep while camping out.
3) Canada does not allow hand guns. Do not bring one. If caught you will go to jail.
4) A semi-automatic shot gun with slugs is the only way to ward off Grizzly and Big Brown bear. Pepper spray works too - if you are not hungry.
5) Keep your food away from where you camp. This way you will hear the bears before they enter your tent.
6) Towns are usually 200 miles apart in the Yukon, British Columbia, and Alaska. But fire truck drive between these towns nightly looking for road wrecks. If you run out of gas, sometimes they will help you out.
7) Getting picked up as a hitch hiker is easy in BC, Yukon, Alaska. Its part of the culture to pick them up. But you may find that you are being picked up in order to drive a guy who is too drunk to drive or has smoked too much hooch. Don't carry the shot gun.
8) Always pass a moose on its hind side. They can't walk backwards but weight 1200lb and will crush you if you pass in front and they run into your way.
8) Stay away from Moose if it has young. The neck and its horns can flip a Chevy - or toss you to your death. Its easy to be taken by surprise stumbling across them in closed small fields where you may have surprised them as well.
9) The distances are emence. Do not be in a hurry "to get there" after the 5th day. If you do you will run over a porcupine and it will flatten your tires. You can eat porkupine when in the Yukon because they don't have trichinosis. Just gut them, burn off all of the quills on a fire then roast em. Taste like pork.... go figure.
9) If you are up there durring the 4th of July, get invited to a local pot-luck. They usually serve local delicacies (elk, moose, king crab, clams, bear, and.... beaver). Some of the best beaver I've ever eaten was Alaskan

.
10) If you smell garbage its probably a bear close to you (they live off trash heaps) and get the hell outa there.
10) If a herd of elk or herbivore of some kind run quickly past you without regard, you should run too - wolfs or some other predators have caused them to run.
11) Bring a fishing pole and get a license.
12) The low tides on the Alaskan shore will reveal thousands of mussles, cockels, and clams of all sorts. Good eats if you are hungry. Check for red tide warnings before you eat them. Thats how 1/3 of Captain Cook's crew died.
12) Fresh road kill is edible - if you see it being killed. Tarmagan are a wild grouse which are always flying out in front of the rarely passing vehicle. Again, good eats.
13) Alaskan woman are ALWAYs on the hunt. Beware they are good at it.
14) There and back will be a grind - especially on a motorcycle. But people walked the distance during the Klondike gold rush.
15) In Alaska out back you are food.
16) If you see a dust cloud 20 miles away, beware, it will usually be a driver hauling at over 100 mph who "is" in a hurry. When he passes you he may be in the middle of the road and not see you.
17) Try not to kill your travel buddy's after the first 8 days. Just put some distance between you and them and agree to meet up someplace after 500 miles. They will number in the few of your assets.