Understatement of the year - and it's early morning, January 1st.

Compared to Europe, in the U.S. it's tedious and super expensive.
Amtrak remains the best option - if you have the time.
And if you and/or your destination is within 300 miles of an Amtrak station.
(And if that station has bike or roll-on service.)
(And if Amtrak's long distance routes will be around by the end of the year.)

MSN is right about all the extra fees - airlines are awful, but so is Greyhound.
A shout-out to Oregon's regional busses - unboxed bikes and panniers are fine underneath.
StayHeap used to rec one-way car/van rentals,
but those have gotten outrageously expensive, if they are even available.

Safe touring, everybody! And Happy New Year.