We've noted before that Iowa and New Hampshire are whiter than the rest of the country; it was part of my argument one year ago that the first state to vote should be one like California, not Iowa.
It's particularly important this year because the overwhelming whiteness of the early states favors Sen. Bernie Sanders of Vermont. There are a number of deep fault lines between the two Democratic candidates for their party's nomination, including age (Sanders dominates with younger voters), gender (Hillary Clinton does much better with women) and income (Sanders is favored by lower-income voters). But there's also a split on racial lines, which we've noted before. Clinton does much better with nonwhite voters — and in Iowa and New Hampshire, those are in short supply. Hence, the close call in Iowa and the loss in New Hampshire.
The Census Bureau breaks out race and ethnicity separately, counting whites, blacks and Asians separately from Hispanics. Since the 1981 Census estimate, the population of each state that is non-Hispanic white has dropped — far more in some states than others. Below, the change in the percentage of each state that is nonwhite since 1981.
Iowa and New Hampshire are right at the top.
(We excluded Hawaii, because it sort of breaks the scale, with a non-Hispanic white population of 22.9 percent in 2014.)
Further down, you see the next two states to vote, Nevada and South Carolina. Their populations are far less homogeneous, which isn't a guarantee of victory, but which bodes well for Hillary Clinton.
To some extent, this graph also tells the story of the Donald Trump campaign. As America has gotten less uniformly white, it has changed the country culturally. There's an undercurrent to Trump's support that is a tacit response to how the lines on the chart above keep sliding downward, though how much of an effect that's had is hard to say.
You may have noticed that there are a few states that are more uniformly white than New Hampshire. The odds are good that Sanders will do well there, too. After all, one is Vermont.