Results & measures · Presidential elections
Two-party vote share
A party's share of just the Democratic + Republican votes, excluding everyone else.
Two-party vote share divides one major party's votes by the Democratic and Republican votes combined, ignoring third-party, independent, and write-in votes. By construction, the Democratic and Republican two-party shares always add to exactly 100%.
It's the cleanest measure for comparing elections across years, because the third-party vote varies enormously — nearly 19% of the 1992 vote went to Ross Perot, while recent elections have run under 2% 'other'. Raw vote shares absorb that noise; two-party share removes it.
Also known as: two-way vote share, major-party share.
See two-party vote share in the data
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Two-party vote share — FAQ
What is two-party vote share in election results data?+
A party's share of just the Democratic + Republican votes, excluding everyone else. Two-party vote share divides one major party's votes by the Democratic and Republican votes combined, ignoring third-party, independent, and write-in votes. By construction, the Democratic and Republican two-party shares always add to exactly 100%.
Why does two-party vote share matter?+
It's the cleanest measure for comparing elections across years, because the third-party vote varies enormously — nearly 19% of the 1992 vote went to Ross Perot, while recent elections have run under 2% 'other'. Raw vote shares absorb that noise; two-party share removes it.
Where does this election results data come from?+
County-level presidential returns come from the MIT Election Data and Science Lab (MEDSL). pumsdata is an independent product and is not affiliated with MEDSL or with any campaign, party or election authority.