| 1 | 1974 New Hampshire | Louis C. Wyman def. John A. Durkin | 0.00 pts |
| 2 | 2008 Minnesota | Al Franken def. Norm Coleman | 0.01 pts |
| 3 | 1964 Nevada | Howard W. Cannon def. Paul Laxalt | 0.04 pts |
| 4 | 1974 North Dakota | Milton R. Young def. William L. Guy | 0.07 pts |
| 5 | 1924 Iowa | Smith W. Brookhart def. Daniel F. Steck | 0.08 pts |
| 6 | 1998 Nevada | Harry Reid def. John E. Ensign | 0.09 pts |
| 7 | 2000 Washington | Maria Cantwell def. Slade Gorton | 0.09 pts |
| 8 | 1944 Missouri | Forrest C. Donnell def. Roy McKittrick | 0.12 pts |
| 9 | 2018 Florida | Rick Scott def. Bill Nelson | 0.12 pts |
| 10 | 2016 New Hampshire | Maggie Hassan def. Kelly Ayotte | 0.14 pts |
| 11 | 2002 South Dakota | Tim Johnson def. John R. Thune | 0.15 pts |
| 12 | 1954 New Jersey | Clifford P. Case def. Charles R. Howell | 0.19 pts |
| 13 | 2024 Pennsylvania | Dave McCormick def. Robert P. Casey Jr. | 0.22 pts |
| 14 | 1962 South Dakota | George McGovern def. Joe Bottum | 0.24 pts |
| 15 | 1970 Indiana | Vance Hartke def. Richard L. Roudebush | 0.24 pts |
| 16 | 1914 Wisconsin | Paul O. Husting def. Francis E. McGovern | 0.31 pts |
| 17 | 1938 Indiana | Frederick Van Nuys def. Raymond E. Willis | 0.33 pts |
| 18 | 1938 Iowa | Guy M. Gilette def. Lester J. Dickinson | 0.33 pts |
| 19 | 1996 Louisiana | Mary L. Landrieu def. Louis Woody Jenkins | 0.34 pts |
| 20 | 2024 Michigan | Elissa Slotkin def. Mike Rogers | 0.34 pts |
| 21 | 1946 Maryland | Herbert R. O'Conor def. David J. Markey | 0.36 pts |
| 22 | 1974 Nevada | Paul Laxalt def. Harry Reid | 0.37 pts |
| 23 | 1978 Virginia | John William Warner def. Andrew P. Miller | 0.38 pts |
| 24 | 1956 Pennsylvania | Joseph S. Clark def. James H. Duff | 0.39 pts |
| 25 | 2006 Virginia | James H. Jim Webb Jr. def. George F. Allen | 0.39 pts |