Why We Love It

Who won the election and was it by a landslide or a thin margin? We love that this map lets you zoom into regions within each state, to investigate variation hidden within final totals and see voting patterns along with close calls. A map like this would be valuable to politicians looking for battleground areas, or anyone who wants to see how people vote from city to city.

Why It Works

This map gives an in-depth look at the 2008 US presidential election. We’ve all seen a “red state, blue state” map, but what sets this one apart is that it shows areas where the vote was close, highlighted in white. These “on the bubble” areas are where a campaign manager might want to invest more energy.

Important Steps

Use ArcMap to create this map.

By querying the data, you can create separate layers to show who won each precinct.

The size of the symbol is based on the number of votes, using graduated symbols.

Once the map is working well at the target scale (in this case, 1:576,000), you can add more map layers to make the map the best it can be at each scale.

Create a map service (cached tiles) and make it public.



You will need voting district boundaries and numerical data to show how far locations are from a middle value, for example 50% of the popular vote. This map shows election results, but you can make a similar map using any numeric data that naturally falls on either side of an important breakpoint.


For this map we had to decide what could be considered a close vote at the precinct level. Campaign organizers often pay close attention to any precinct where their party won or lost by 5% or less. The 5% figure was used to visually call out the “on the bubble” precincts.


It should take you one day for setup and one day for caching.



By adding a white line around red and blue circles to show places that are close to a 50% voter turnout, we can show a second and important piece of information. Symbols that say two things are called “bivariate.”

More Information

Map Author

Jim Herries

Jim Herries

@jherries | LinkedIn

Applied geographer, map curator for Living Atlas of the World and Urban Observatory. I work with talented people to make better maps by eliminating the noise and increasing the signal.

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