a state border is the border of state
Dumas Junction, Texas. (nope, not kidding).
Maine IS a border state
None. A border defines the boundary of a state therefore no state will cross the border of another state.
the border state
The California-Nevada state border.
All states but Alaska and Hawaii border at least one other state. Maine is the only state to border just one state.
The border state of Maryland was a central state in the US Civil War, and had the border state of Delaware on its east, the Union State of Pennsylvania to its north, and the Confederate state of Virginia to its south.
New Hampshire is the only state to border Maine.
Montana does not border Mexico.
Columbus is entirely within Ohio. It does not border any other state.
Alaska and Hawaii do not border any other state.