Originally Posted by
fietsbob
Well, Columbia River (Gorge) kept cutting thru the mountains,
as the Cascades were pushed up, by geological forces.
Sierras and the rest of the Cascades, you have to go over them..
Hmmm...I can think of Highway 70 along the Feather River that has cut through the northern Sierra in much the same way, but then you have to cross all the ranges in the Basin and Range area anyway. Much the same deal with going up the Sacramento River to Mt. Shasta to reach the Modoc lava plateau, there's still a lot of climbing after that.
People have ridden across the country in 7-8 days during the Race across America, so anything is possible. You tell us nothing about your level of fitness, what you're carrying, where you plan to sleep, and then want us to give you an answer?
The fastest route may be the southern tier until you reach the southerly low level wind flow that comes up from the Gulf during the warm months, then head northeast toward New York. This would not be the most scenic or most comfortable route, weatherwise.