Minnesota and Michigan first played football in 1892. They did so again in 1893 and 1895, then didn't hook up until 1903.
Fielding Yost had Michigan on a 28-game winning streak when it came to Minneapolis for the game at Northrop Field. The trust level among college competitors wasn't very high, apparently.
Yost had a student manager buy a water jug rather than accept a supply given to him by the Minnesota side. The coach feared that rabid Minnesota fans might contaminate the water supply if Michigan wasn't able to monitor it properly.
Minnesota scored late for a 6-6 tie, sending 20,000 fans into a frenzy. In the chaos, the Michigan water jug was left behind. L.J. Cooke, the head of athletics at Minnesota, had the jug painted and the 6-6 score added to it.
Michigan and Minnesota didn't play until 1909. The message from the Minnesota side was that if Michigan wanted back its water jug, Michigan had to win it back. Thus, the Little Brown Jug was introduced, and became the oldest traveling trophy in college football.
Minnesota and Michigan played every autumn from 1919 through 1998 -- 80 seasons in a row. For the first 50 of those seasons, Michigan was the No. 1 rival on Minnesota's schedule ... not Iowa, not Wisconsin, Michigan.
The arrival of Penn State gave the Big Ten an odd number of teams and shook up the schedules. The Gophers-Michigan series was interrupted in 1999 and 2000, and again in 2009 and 2010. Then Nebraska came along to make it 12 teams, Michigan and Minnesota wound up in the same division, and it appeared the Little Brown Jug rivalry was secure.
Iowa was also in the same division, so that took care of the second important rivalry game for the Gophers. And the protected game with the other division was Wisconsin, so all the ancient rivalries for the Gophers were preserved.