Seventy-five congressional races in 2020 were decided by 10 percentage points or fewer, including eight for U.S. Senate and 67 for U.S. House. Thirty-five races were decided by fewer than five percentage points; three of those were U.S. Senate races and 32 were U.S. House races.

Democratic candidates won 40 of these elections and Republican candidates won 35. Out of the races decided by fewer than five percentage points, Democrats won 22 and Republicans won 13.

Fourteen U.S. House races remained uncalled as of Nov. 18, and eight seemed likely to be decided by fewer than 10 percentage points.

In comparison, 102 races were decided by 10 percentage points or fewer in 2018. Of these, 12 were elections for the U.S. Senate and 90 were elections for the U.S. House. Democratic candidates won 49 of these elections and Republican candidates won 53.

Fifty races in 2018 were decided by fewer than five percentage points: five elections for the U.S. Senate and 45 elections for the U.S. House. Democratic candidates won 24 of these elections and Republican candidates won 26.

There were 42 and 56 congressional races decided by 10 percentage points or fewer in 2016 and 2014, respectively. In 2016, nine were elections for the U.S. Senate and 33 were elections for the U.S. House, with candidates from each major party winning 21 of the elections. In 2014, seven were elections for the U.S. Senate and 49 were elections for the U.S. House. Democratic candidates won 32 of these elections and Republican candidates won 24.

For races decided by fewer than five percentage points, there were 22 in 2016 and 31 in 2014. In 2016, five elections were for the U.S. Senate and 17 were for the U.S. House seats, with Democratic candidates winning 14 of these elections and Republicans winning eight. In 2014, five were elections for the U.S. Senate and 26 were for the U.S. House, with Democratic candidates winning 17 of these elections and Republican candidates winning 14.