Smart Politics examined all U.S. Senate elections since 1990 and found that North Carolina leads the nation with its 10 contests decided by an average victory margin of 6.1 points.

“The Tar Heel State has consistently produced competitive races going back several decades, with 14 of its last 15 U.S. Senate elections decided by single-digits since 1978.”

“Only six other states have averaged victory margins in the single digits since 1990: Colorado (8.5 points), Pennsylvania (8.9), Missouri (9.1), Nevada (9.5), New Jersey (9.6), and Minnesota (9.9). Five of these states host senate races in 2018 with three expected to be particularly hard fought (Missouri, Nevada, and Pennsylvania).”