The highway (a.k.a The Haul Road, to the local trucker community) runs from the Elliot Highway (a fair way north of Fairbanks) and ends at Prudhoe Bay, which is the furthest north you can reach by permanent highway in North America. Truly "the end of the road"... it is essentially a wilderness highway, and the few "towns" along the way, with some exception, offer almost nothing in the way of hitch-hiker friendly amenities. In other words, come fully prepared to be out in the wild.
As was stated, the Dalton Highway is essentially a wilderness highway, half of which is within the Arctic Circle, so some precautions must be taken that might otherwise not be considered. First and foremost do not attempt to hitchhike the Dalton in the winter... this may seem obvious to most people, but it should be laid out clearly. Temperatures easily drop to -40 (F and C, since that's the point on the scale that they're exactly equal), and this is compounded by snow, extreme windchill, and little to no sun-light. In fact, hitchhiking should only be attempted on the Dalton from mid-May to mid-Sept (with late May, early June, and Mid August probably being the best and most comfortable times)... keep in mind, it literally never gets dark for most of the summer on most of the highway.
Encounters with dangerous wildlife, particularly bears (Brown and Grizzly, and Polar near the Arctic Ocean) and the ever erratic moose are very possible. Because of this, you should come equipped with pepper spray or a firearm. Keep in mind the sensitivities of your potential drivers, and only keep your animal deterrents handy when necessary (i.e., while camping down for the night, or while hiking through dense brush). Also keep in mind that gun toting is very common in Alaska, so don't be surprised if your driver is packing. Also, you should never camp near Prudhoe Bay, or most of the "North Slope" (the far north Tundra area) due to the potential risk of Polar Bears.
Mosquitoes will be out in unbelievable force from June through mid August. Repellent is basically useless, so bring (at least) a head net, with a pancho-style-net probably being the best bet. Trust me, there aren't words to describe how bad the mosquitoes can be, so absolutely come prepared for them, or be sucked dry in no time.
Amenities on the road
There are pretty much no amenities on the road. There are two small cafes near the Yukon River bridge, a small cafe at Coldfoot (selling short order food, and very limited supplies like bread and lunch-meat) and a slightly better stocked store at Prudhoe. All of these are 100's of miles apart.
There isn't much in the way of developments on the road, so your rides, though likely infrequent, will be long and far. The best place to get started from the Fairbanks area is probably the Hilltop Cafe north of Fairbanks... Axiomaticdrifting swears there used to be a public bus that ran there from Fairbanks, but he can't find any info about it right now. The Hilltop is frequented by most of the truckers that work the highway back and forth so try and get a ride at least to Coldfoot from here. Coldfoot is a good place to explore the brooks range and still have access to the road traffic, it is also officially within the Arctic. It really doesn't matter where you get a ride to, though, since it's a two way road with pretty much nowhere else to go but north or south... so, really take what you can get, and you'll eventually get where you're going. Any rooms you might find along the way (at Yukon, Coldfoot, Wiseman, and Prudhoe) will be ridiculously expensive ($150 and up), and won't be worth the money, so come prepared to camp. At that, most of the land surrounding the road, with the exception of the land immediately around the oil pipeline, is public, so camp wherever you want unless it's obviously owned by someone. Good destinations to aim for on your first day from Fairbanks would be The Yukon River Crossing, Coldfoot, Wiseman, or any Pump Station along the pipeline... all these places will see all traffic on the road, will be safe for drivers to stop, and you'll likely be able to actually converse with drivers in person there. From the aforementioned locales, it's up to you whether you want to go all the way to Prudhoe or not. I would advise against going there unless you're willing to cough up the money for a room or are willing to turn around and try to hitchhike back south on the same day (again, camping can be especially dangerous in Prudhoe with the risk of Polar Bears, but it almost certainly has been done before... so... yeah)
Panamericana, a male/female couple hitching the Dalton in June 2012, claims that trucks and other commercial or state vehicles WILL NOT pick you up on the Highway. It's against their insurance and company policies, and though many are very apologetic and may give you food/water/bug spray/sympathy, you're not going to get commercial lifts. For this reason we would disagree with the Hilltop Cafe as a place to start, but we hitched a ride within half an hour from the road outside the nearby Weigh Station. (This is a few miles from Fairbanks but from town you can walk out to where the road to Fox starts which is the one you want, followed by the Elliot Highway to get you to the start of the Dalton.) However, Axiomaticdrifting has successfully hitched rides on the Dalton from commercial vehicles on multiple occasion.
Lots of tourists go to the Arctic Circle (mile post 115) so it seems pretty easy to get there, but after that you're looking for some very good luck.
Unless you are planning to pay $45 each for a short trip out to the Arctic Ocean (no individuals allowed. There's big fences), there really is nothing in Deadhorse (the oil camp at Prudhoe Bay.) We'd also add to places being expensive that they're extremely unfriendly, and we weren't even allowed to warm up in the hotel unless we bought expensive food, nor could we share one plate of breakfast between two.
Camping equipment is indeed essential, as is plenty supplies and anti-bug gear. On the way down we got stuck for two days (we were still above the Arctic Circle), but as already said when someone does eventually pick you up, they'll be going your way!
Hope this doesn't all sound too negative as the Highway is beautiful, but just remember its a wilderness adventure. trash:Alaska