Average U.S. House margin of victory on track to be narrower than 2018, setting a decade-low record

The average margin of victory among U.S. House races that were callable as of Nov. 18 was 30.0 percentage points, the narrowest since at least 2012, according to a Ballotpedia analysis. The previous record low was 30.2 percentage points in 2018. The average margin of victory in callable U.S. Senate races was 18.9 percentage points, wider than the 16.8 percentage point average in 2018 but narrower than in any other year since 2012.

The narrowest margin of victory in any callable race was Burgess Owens’ (R) 0.57 percentage point margin over incumbent Ben McAdams (D) in Utah’s 4th Congressional District. McAdams defeated incumbent Mia Love (R) by a 0.26 percentage point margin in 2018, that year’s second-closest U.S. House race.

The narrowest margin of victory in the U.S. Senate was incumbent Gary Peters’ (D) 1.35 percentage point margin over John James (R) in Michigan. Peters’ win was the fifth-closest by overall number of votes. The U.S. Senate race decided by the fewest votes was incumbent Steve Daines’ (R) 31,000-vote win over Steve Bullock (D) in Montana.

The widest margin of victory, excluding uncontested races, was Neal Dunn’s (R) 96.1 percentage point margin over write-in Kim O’Connor (I) in Florida’s 2nd Congressional District. Among U.S. Senate races, the widest margin was Cynthia Lummis’ (R) 46.1 percentage point margin over Merav Ben-David (D) in Wyoming.

Ballotpedia’s analysis of Congressional margins of victory will be updated and expanded as final certified results become available.