The 1947 college football season finished with Notre Dame, Michigan and Penn State all unbeaten and untied, but the Fighting Irish of Notre Dame were the first place choice for 107 of the 142 voters in the AP Poll, and repeated as national champions. Michigan went on to meet USC in the Rose Bowl and won 49-0, while Penn State was tied 13-13 by SMU in the Cotton Bowl Classic, and Notre Dame didn’t participate in the postseason. An unofficial post bowl AP poll was conducted with Michigan and Notre Dame as the only options and Michigan won by a vote of 226 to 119.
During the 20th century, the NCAA had no playoff for the college football teams that would later be described as "Division I-A". The NCAA did recognize a national champion based upon the final results of the Associated Press poll of sportswriters (the UPI Coaches Poll would not start until 1950). The extent of that recognition came in the form of acknowledgment in the annual NCAA Football Guide of the "unofficial" national champions.
The Associated Press did not poll the writers until after the games of October 4. Among the five teams that had been ranked highest in 1946 (Notre Dame, Army, Georgia, UCLA and Illinois).
Georgia opened on September 20 with a 34-7 win over Southern Mississippi in (site). UCLA hosted Iowa the following Friday and won 22-7.
The next day, September 27, Army beat Villanova 13-0, Illinois beat Pittsburgh 14-0, and Georgia beat Tennessee, 27-0.
On October 4 Notre Dame won at Pittsburgh 40-6. Army shut out visiting Colorado 47-0. Georgia beat Tulane in New Orleans, 20-0. UCLA lost at Northwestern 27-26.
Illinois won at Iowa 35-12. When the first poll came out that Monday, Notre Dame was the favorite of a bare majority (52 of 103) of the voters, followed by Michigan, Texas, Georgia Tech and Army. Illinois was ranked 6th, Penn 7th, California 8th and Georgia was ranked 9th.
On October 11 #1 Notre Dame won at Purdue, 22-7. #2 Michigan beat Pittsburgh, 69-0. In Dallas, #3 Texas beat #15 Oklahoma 34-14. #4 Georgia Tech beat VMI, 20-0, for its third shutout in three starts. #5 Army and #6 Illinois met at Yankee Stadium in New York, and played to a 0-0 tie. #8 California, which won at Wisconsin 48-7, rose to fourth.
October 18 #1 Michigan won at Northwestern, 49-21. #2 Notre Dame shut out visiting Nebraska, 31-0. #3 Texas met Arkansas at a neutral location in Memphis, Tennessee, and won 21-6. #4 California beat Washington State, 21-6. #5 Georgia Tech defeated Auburn 27-7 to stay unbeaten, but was voted out of the Top Five. #6 Illinois, which beat #13 Minnesota 40-13, rose to fifth.
October 25 #1 Michigan stayed unbeaten, with a 13-6 win over Minnesota, as did #2 Notre Dame, which defeated Iowa, 21-0. #3 Texas beat Rice, 12-0. #4 California lost to #10 USC, 39-14. #5 Illinois lost at Purdue, 14-7. #8 Penn beat Navy, 21-0. The Irish rose to #1 in the next poll, with a 78-69 lead in votes over Michigan.
November 1 #1 Notre Dame and Navy met in Cleveland, with the Fighting Irish registering their third straight shutout, 27-0. #2 Michigan won at #11 Illinois, 14-7. In Dallas, #3 Texas (6-0-0) faced unbeaten (5-0-0) #8 Southern Methodist University (SMU), and the SMU Mustangs won 14-13. #4 Pennsylvania won at Princeton, 26-7, to stay unbeaten. In Seattle, #5 USC beat Washington 19-0.
November 8 #1 Notre Dame hosted #9 Army and won 27-7. #2 Michigan beat Indiana 35-0. #3 SMU won at Texas A&M, 13-0. #4 Pennsylvania beat Virginia, 19-7. #5 USC beat Stanford, 14-0.
November 15 #1 Notre Dame had more points scored against it than at any other time in the season, but won at unranked Northwestern, 26-19. Meanwhile, #2 Michigan faced #9 Wisconsin in Madison and won 40-6, raising it to first place in the next poll. #3 Pennsylvania and #13 Army played to a 7-7 tie in Philadelphia. #4 SMU stayed unbeaten with a 14-6 win over Arkansas. #5 USC was idle.
November 22 #1 Michigan closed its season at 9-0-0 with a 21-0 win over Ohio State, and accepted an invitation to meet #4 USC (which beat #18 UCLA 6-0) in the Rose Bowl. Meanwhile, #3 SMU won 10-0 win at Baylor, and #5 Penn State won at Pitt, 29-0. Both unbeaten, they accepted invitations to the Cotton Bowl Classic. #2 Notre Dame thrashed Tulane, 59-6 and was restored to the top spot by the AP voters, with 97 first place votes to Michigan's 81.
November 29 #1 Notre Dame, #2 Michigan, #4 USC, and #5 Penn State were idle. #3 SMU was tied in a game at TCU, 19-19.
December 6 #1 Notre Dame (8-0-0) and #3 USC (7-0-1) met in Los Angeles, with the Irish cementing their hold on the #1 ranking, 38-7. #2 Michigan, #4 SMU and #5 Penn State had completed their seasons.