The playoff seeding system was started in 1975. Since then, every Super Bowl has featured at least one #1- or #2-seeded team.
In the following table, #1 and #2 seeded teams are bolded. Years marked with a '*' are ones with no #1 seeded team. As usual, the year refers to when the regular season started; the actual Super Bowls are played the following calendar year.
| Year | Winner | Loser | |
| 1975 | Steelers #1 | Cowboys #4 | |
| 1976 | Raiders #1 | Vikings #1 | |
| 1977 | Cowboys #1 | Broncos #1 | |
| 1978 | Steelers #1 | Cowboys #2 | |
| 1979 | Steelers #2 | Rams #3 | * |
| 1980 | Raiders #4 | Eagles #2 | * |
| 1981 | 49ers #1 | Bengals #1 | |
| 1982 | Redskins #1 | Dolphins #2 | |
| 1983 | Raiders #1 | Redskins #1 | |
| 1984 | 49ers #1 | Dolphins #1 | |
| 1985 | Bears #1 | Patriots #5 | |
| 1986 | Giants #1 | Broncos #2 | |
| 1987 | Redskins #3 | Broncos #1 | |
| 1988 | 49ers #2 | Bengals #1 | |
| 1989 | 49ers #1 | Broncos #1 | |
| 1990 | Giants #2 | Bills #1 | |
| 1991 | Redskins #1 | Bills #1 | |
| 1992 | Cowboys #2 | Bills #4 | * |
| 1993 | Cowboys #1 | Bills #1 | |
| 1994 | 49ers #1 | Chargers #2 | |
| 1995 | Cowboys #1 | Steelers #2 | |
| 1996 | Packers #1 | Patriots #2 | |
| 1997 | Broncos #4 | Packers #2 | * |
| 1998 | Broncos #1 | Falcons #2 | |
| 1999 | Rams #1 | Titans #4 | |
| 2000 | Ravens #4 | Giants #1 | |
| 2001 | Patriots #2 | Rams #1 | |
| 2002 | Buccaneers #2 | Raiders #1 | |
| 2003 | Patriots #1 | Panthers #3 | |
| 2004 | Patriots #2 | Eagles #1 | |
| 2005 | Steelers #6 | Seahawks #1 | |
| 2006 | Colts #3 | Bears #1 | |
| 2007 | Giants #5 | Patriots #1 | |
| 2008 | Steelers #2 | Cardinals #4 | * |
Comments:
There's certainly evidence in this list that high playoff seeds aren't as valuable as they used to be:
There were 8 #1-vs-#1 matchups 1975 to 1993 (19 seasons).
There were 0 #1-vs-#1 matchups 1994 to 2008 (15 seasons).
Counting this year, we are on a stretch of 5 Super Bowls not won by a #1 seed. The longest such strech before 2000 was just two years (1979-1980, and 1987-1988).
