Top 3 oldest rivalries(not including military academies):Michigan v Ohio St, Oklahoma v Texas, and Alabama v Auburn.
I don't have a definitive answer to this one, but the above Answer is wrong. Harvard and Yale have been playing football against each other since 1875. Many other long standing rivalries come up when you simply search for them on the internet. Lehigh vs Lafayette (since 1884), South Dakota School of Mines and Technology vs Black Hills State University (said by Wikipedia to be the second most played after Harvard-Yale), Wisconsin vs Minnesota (since 1890) and many others. The Wikipedia entries say the first Michigan - Ohio State game was in 1897, Auburn-Alabama in 1893 and Oklahoma - Texas in 1900.
The original Question is too vague. Why are service academies excepted? Did they mean ONLY current FBS football schools? The Answer above sounds like a 9-tear old's vision of "oldest college football rivalries": that is, only the currently popular football team rivalries that the nine year old has heard of.
Does the question mean the oldest first game between two rivals? The rivalry with the longest consecutive years played to date? Many rivalries are initially old but some years the game is not played. The rivalry with the highest number of games played? Are all football divisions included, or just the current major college programs?
Harvard - Yale is VERY likely the number ONE answer to this question. After that, you must specify what the question really means to get a definitive answer.
The Ohio State Buckeyes and The Michigan Wolverines.
Harvard vs. Yale- started in 1875
Yale - Harvard
Army Navy Rivalry.
michigan ohio state
The Ohio Stat university with 17 wins longest current winning streak in division 1 ncaa football
According to the NCAA records book, this is the fourth-longest rivalry in Division I-AA football, and according to I-AA.org, it's the eighth-longest all-time in all divisions. The teams first met in 1898, and have played 114 games through 2004 (so this year's should be 115) ... The Tribe leads the Spiders in the series 59-50-5. -- Keith, of D3football.com
Duke blue devils
University of Colorado