Cook Partisan Voting Index

The Cook Partisan Voting Index is the unit used to calculate how much a particular state or congressional district leans towards each political party.

A map of the Cook PVI in each state. Blue is used for the Democrats, while red is used for the Republicans. Darker colours indicate that a state has a heavy lean toward one party or the other, whereas lighter colours indicate a less substantial lean.

By state

All 50 states in the United States lean either towards the Democrats or Republicans. The most Democratic-leaning state, according to the CPVI, is Vermont, which is D+16 on the CPVI scale (meaning that, in a normal election, the Democratic candidate should start with an advantage of approximately 31 points over the Republican candidate there). On the other hand, the most Republican-leaning state, Wyoming, has a CPVI score of R+25, meaning that the Democrat will have a 51% edge against their Republican opponent in a neutral election.