I agree with Pete. Your ride, your definition.
And while an ocean doesn't really technically matter to its definition, the question is where does the nation end, i.e. at the water's edge (high or low tide), the 12?? mile exclusive fishing territory, or
? Do we have to get to Attu Station, AK or would Tanana, AK, work since it is the furthest west contiguous road in the USA? Or do we have to start in Puerto Rico and end in Guam.
I personally like dipping the wheels though I am relaxed as to whether it is high tide or low tide
. However, I am lazy so only dip if it is easy, i.e. finding a paved boat ramp so I don't have to wade through sand. If that is not readily available, being on the road close to the ocean is good enough for me as I firmly believe if you get to just the road near the ocean, that is fine, i.e., no dipping required. I',m just anal about the "entire" way.
I also don't think you need to go to the furthest point to satisfy the cross country aspect, within reason. For instance, both the Southern Tier and the TransAm are both cross country trips. However, looking at a map, the TA was a greater latitude length than the ST but, to me, riding from Fort Lauderdale to Fort Myers, Florida, does not qualify as cross country though I guess technically it does.
I start to question if it is a full cross country ride the further you get away from the coast. For instance, I personally would not count Washington, DC to Seattle a true FULL cross country trip but just a cross country trip. Yeah, the definition sucks but it is sort of the same lines as what is a self-contained tour (let's not go there on this thread).
If I were joining you, I would start early and head out of Norfolk/Virginia Beach on the upcoming DELMARVA Route and head out to Chincoteague Island (want to see the horses) in Delaware before taking the ferry over to Ewell/Tangier Island to the Tidewater Potomac to DC to start the Eastern Express. I would end in the San Juan Islands (probably Victoria, BC, as I love Butchart Gardens).
BUT THAT IS ME!!! You do what you want since you are the one riding.
Also, does riding from Mexico (or the Gulf of Mexico) to Canada count as a cross country trip? To me it does, primarily because I have done it 3 times
.
There are all kinds of ways to look at this. My best guess is land border to land border or within 10 miles of such. That said, I still think Pete's answer is the best overall.