Electoral Maps All Look a Little Different. Here’s Why
Every map makes compromises. The Mercator projection, which sacrifices accurate geography for nice, straight lines, is a classic example. Electoral cartograms, which visualize the political climates of individual states, are another.
“They’re all working off the same data, but there’s lots of room to make choices and prioritize information,” says Noah Veltman, a data visualization expert on WNYC’s data news team. So the same data can end up looking pretty different—as in this morphing animation, which Veltman created. It compares cartograms from FiveThirtyEight, the Washington Post, the Wall Street Journal, NPR and Daily Kos, to illustrate how different designers go about presenting electoral data.
None of the cartograms in Veltman’s animation looks anything like your typical US map. The Daily Kos map comes close; its states are all the same shape as the ones you might find in, say, a Rand McNally road atlas. But, like most electoral cartograms, each state is sized in relation to its political weight. A state’s geographic area, after all, rarely corresponds with its electoral power. By land size, Alaska is the biggest state in the country—but it’s one of the smallest in population, so it receives just three electoral votes. Rhode Island, by comparison, which is more than 400 times smaller than Alaska in terms of area, receives four.
To see how electoral cartograms differ from each other, consider the unique spin each map puts on the Great Lakes region. Every configuration looks a little different. And yet, they all manage to preserve the general shape and position of Michigan’s twin peninsulas and its eponymous body of water. All except one, that is: NPR‘s map depicts Michigan as single square, and omits the lake altogether.
That was intentional. “The other maps are grid cartograms, working off hexagon, diamond, or square shaped cells, where each cell equals one electoral vote,” says NPR designer Allison Hurt. “But mine uses a single block for each state, sized by the number of electoral votes the state receives.” Hurt’s approach kept her from depicting Michigan in two pieces, but it also allowed her to divide Maine and Nebraska into multiple segments, to reflect the fact that those states split their electoral votes.
The other cartograms have idiosyncrasies, too. Veltman’s morphing map highlights structural ones—like The Wall Street Journal‘s decision to isolate Washington D.C. from the lower 48—but clicking through to the respective outlets reveals variations in color, shape, and function, as well. FiveThirtyEight tints its hexagonal cells either red or blue. WaPo color-codes its diamond-shaped cells similarly, but also identifies toss-up states with a distinguishable shade of purple. Others incorporate an interactive element; clicking and holding a state on WSJ‘s map, for instance, lets you “flip” it from red to blue, or vice versa, with swing states flipping more readily than stronghold states.
Considered alongside Veltman’s map, these differences are a helpful reminder of how difficult it can be to convey a wide range of information in a single cartogram. “These are all valid directions, but there’s judgment that goes into maps like this,” Veltman says. That’s a good thing to keep in mind in the weeks ahead. The next time you find yourself poring over a political map, remember to check a second—or third, or fourth—for additional insights.