Is there another significant CFB rivalry between teams from non-contiguous states (or the same state)? (Leave ND out.) I can't think of one.
I think one requisite is to play often, if not every year. I guess Florida-LSU is something of a rivalry, but contrived by scheduling. Texas-Nebraska was once a great series. If I'm forgetting one, it's because there aren't many of them.
Play nearly every year
Geographic proximity
Some level of consistent national importance (usually)
As far as I could tell, Texas-Nebraska was not a great series. More like a miserable experience for Nebraska over its time in the Big 12. They've played 14 times, and Texas leads 10-4. Nebraska led 3-1 in the 4-game OOC "series" that was spread out over 42 years. The Big 12 record was Texas 9-1. The 9 Texas wins included 8 heartbreakers for the Huskers.
1996, first-ever Big 12 CCG: Texas 37, Nebraska 27
1998: Texas 20, Nebraska 16
1999: Texas 24, Nebraska 20
1999, Big 12 CCG: Nebraska 22, Texas 6
2002: Texas 27, Nebraska 24
2003: Texas 31, Nebraska 7
2006: Texas 22, Nebraska 20
2007: Texas 28, Nebraska 25
2009, Big 12 CCG: Texas 13, Nebraska 12 (the famous "one second back on the clock" game)
2010: Texas 20, Nebraska 13
OU-Nebraska, now
that was a great series, and between teams in non-contiguous states. In the good ole days of the Big 8, it was the bookend to OU-Texas. Texas--then in the SWC--was often the last game before conference games started, or was played the week after the first conference game. Nebraska was often the next-to-last conference game. OU-Texas was hate mingled with occasional grudging respect. OU-Nebraska was respect occasionally mingled with a little hate. And that series included the
greatest college football game ever played, per ESPN.