FiveThirtyEight introduced its partisan lean metric — a way of measuring the partisanship of a state or district.
“For example, if a state has a FiveThirtyEight partisan lean of R+5, that means it is 5 percentage points more Republican-leaning than the nation as a whole. Put another way, in an election that’s exactly tied nationally, we would expect Republicans to win that state by 5 points.”

