On my first bicycle tour across the country I took most of my bike tools. After less than a week of hauling stuff I didn't need I sent it home to my family. If you are taking a tour in a populated country you will always be able to hitchhike to the next town/bike shop. Therefore I recommend USA bicycle tours only take a few tools:
1. Tubes - I recall I used 8 tubes on my first cross country tour. carrying two extra tubes is always a good idea.
2. Patch kit - I love Park glueless patches, and I would never tour without at least one box of patches.
3. Pump - Everyone needs a pump, a mini pump is fine.
4. Multi tool - Most cheap multi tools are horrible, don't waste your money on them. I love my Topeak Ratchet Rocket . It provides everything you need in a small package, and the quality can't be beat.
5. Spoke wrench - Only if you know how to true a wheel, and make sure to get the proper size for your spoke nipples.
6. Tire - Rear tires on a loaded bike will only last about 1000 miles.
That's all you need everything else can be handled by local bike shops by hitchhiking if necessary.