How the black vote carried Andrew Gillum to victory

Andrew Gillum’s campaign always said to count on black voters.

On Tuesday, the Tallahassee mayor’s upset win proved him right.

Gillum’s friend-turned competitor former U.S. Rep. Gwen Graham won the vast majority of counties across Florida in the state’s Democratic primary for governor. But Gillum was able to win where it mattered — which also happens to be where more Democrats are black.

The map below shows Gillum did best in huge counties like Duval and Broward, while Graham won small and medium counties across the state and dominated the vaunted Interstate-4 corridor.

Source: Florida Division of Elections

The few big counties Gillum took - especially Duval, Broward, Miami-Dade and Orange - were enough to push him to more than a third of the statewide vote, giving him a three-point win over the (considered) frontrunner.

What’s more striking is how clearly Gillum benefited from black Democrats.

Imagine this: line up every county in Florida by how many of its registered Democrats (at the time of the primary bookclosing) are black. Divide the line into thirds.

1. The first, least-black third includes counties like Pasco and Sarasota, where most Democrats are white, as well as Osceola, where most are Hispanic. In those counties, Graham beat Gillum by 17 points.
2. The middle counties, like Brevard, Pinellas and Palm Beach, have a moderate share of black Democrats. There, Graham still won, by nine points.
3. But in the blackest third of counties, it was a different story. Those counties, where black voters make up more than a quarter of registered Democrats, went overwhelmingly for Gillum. He won by 15 points. And those counties include heavyweights like Hillsborough, Miami-Dade, Broward and Duval. Of the 18 counties Gillum won, 16 were in this group.

These graphs show how close the relationship was. The more to the right a circle is, the more black people there are among its Democrats. The higher it is, the better each candidate performed there on Tuesday. Gillum’s is nearly a straight line.