What is the least number of US to go from Atlantic to pacific oceans?

I'm having to interpret your question a little because as stated it's not clear. Here's how I'm reading it:

"What is the least number of US states a person must travel through to get from the Atlantic to the Pacific Ocean?"

We'll make the following assumptions:
1. We're not constrained by roads, bridges, etc. That just makes it too complicated and not fun anymore. If two states touch, you can go from one to the other, including those that touch only at a single point (in other Words, you can go directly from Arizona to Colorado at Four Corners).
2. You can't leave the US. You have to start in a state that borders the Atlantic, move to another state, and so on until you reach a state that borders the Pacific (Washington, Oregon, or California). This keeps you from starting in, say, Virginia and then heading EAST until you come around on the other side and get to California, or starting in Florida, sailing across the Gulf of Mexico to Texas, and resuming your journey.
3. "The Atlantic" doesn't include the Gulf of Mexico or the St. Lawrence River/Great Lakes, so you can't start in Texas or Minnesota. If you could, then Texas, New Mexico, Arizona, California (4) or Minnesota, North or South Dakota, Montana, Idaho, Washington or Orgon (5).
4. You can't travel along a border and claim you're not in any state; you have to be "in a state" at all times, though if you're on a border you can choose which of the bordering states you're in.

I get 7, with several ways to do it. One is Virginia, Kentucky (or Tennessee), Missouri, Nebraska, Wyoming, Idaho, Oregon (or Washington). Another is North Carolina (or Georgia), Tennessee, Arkansas (or Missouri), Oklahoma (or Texas, if you chose Arkansas), New Mexico, Arizona, California.