Oil
tools for valve adjust
fuses
light bulbs
air pump/insta tire
various screws/bolts/nuts
tape

of course depends upon the ammenities along the way.

and a sack full of marbles so you can replace the ones that have gone missing at the end of the day.  

Good all weather gear
At least a sheepskin cover for the seat. It's soft and will keep the o'l butt warm.

Since you will be leaving and re-entering the US, make sure you have proper documentation such as a passport. Be sure you have any required documentation for the motorcycle, such as proof of registration. Make sure your motor vehicle insurance is valid in Canada. Check with Canadian Customs so you don't inadvertently carry contraband. If you have prescription medications, make sure they are in the prescription container.

I'd want to make sure the tires had enough life left in them for the trip, which probably means a new rear at least.  I would make sure the motorcycle's maintenance wouldn't come due during the trip, then I wouldn't worry about carrying anything for it except perhaps a quart of oil. It is not likely any major harm would befall should you go overdue on maintenance, in any case. A set of inner tubes might be good insurance, as well as a headlight and taillight bulb. If your battery is more than a couple or years old it might be wise to replace it before you set out.

The old rule for travel: Take half as much "stuff" and twice as much money.

Since your only 19 just get on and ride. In '66 I rode from Windsor Ontario Canada to LA on a salvaged '63 Norton. We did what we had to do and had a hell of a time doing it. According to Google maps that's about 4500 miles on the straightest line they can come up with. Most of those roads didn't even exist back then. Unfortunately the only thing I have left from the trip is memories.    

Log on to advrider.com (join) and research 48 state USA to Alaska trips.Be prepared to enjoy weeks of reading.Then read about the really adventurous trips across the  world.

I've done two round trips from southern MN to Miami, FL and one to SC, in the heat of August on my 650. I hauled a ton of stuff I never touched, but the bike handles it all really well. The FL trips ended up being around 4k miles each.

I suggest using synth oil. You get a lot longer between changes, run several degrees cooler and it smells slightly better if you develop the "dread-oil-plug" leak and have to live with a bit of burn-off aroma.

There's nothing you can do about the stock seat to make it bearable for several days in the saddle. I have a V-Star saddle seat on my bike. Any kind of saddle shape will give you much better support more wiggle around room when it becomes necessary. I have a gel pad that doesn't do much for long term butt-bone comfort, but does absorb a lot of the vibration which is a good thing indeed.

Do some 2-4 hour runs to start getting the bottom built up. I did 200 miles yesterday and the numb is almost gone.

Don't be afraid to stop and look around. Don't be afraid to take what might be an interesting detour. Take a lot of pictures.

Jack