2012 US Minority Populations

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Why We Love It

Who lives where in our country? This map helps answer that question for the US by showing the concentrations of minority populations across the nation according to US Census Bureau data. We love how color intensity is used to represent the percentage of the population for each minority group at the county level. Here, a map tells the story of US history, regional identity, and immigration.

Why It Works

Zoom out to get an overview of the country as a whole. Zoom in to see data by state and county. The transparency of each county is varied using the magnitude of the value mapped—a technique accomplished using the new smart mapping features in ArcGIS. This map works because it answers questions and provokes curiosity that gets us asking more questions.

Important Steps

Add a map layer of county data containing the population counts for each group.

Use the layer’s Change Style tools to show location only as a single symbol with a bold color.

In the style options set the per feature transparency to show population of one of the minority groups divided by the total population, emphasizing values of 0 to 0.20 (20%).

Copy the layer and repeat for other minority groups using different colors.

Copy the layer one more time and configure pop-ups and no symbols on this copy.

Save the web map, add it to a configurable app template, and share.

Requirements

Data

The sample data in the standard USA Counties (generalized) layer available on ArcGIS Online was used.

Analysis

As you style the map using transparency, note the range of values for each layer mapped to see how the values vary by group. Choose a common set of thresholds for the legend so a full-color value means the same thing for all groups.

Time

Total time is one hour, including five minutes to find pre-published Census data on ArcGIS Online and another five minutes per layer to configure in the web map. The balance of time is in configuring the user experience in an app template.

Spread and Density

Tips

Using exactly the same range of values in the layer’s color ramp settings allows direct comparison of the colors.

Logical Grouping

Tips

Pick bold, varied colors for each layer since each color will also be present at a variety of intensities.

Think About Information

Tips

Use an app that enables layer toggling so people can make their own comparisons. Include a copy of the layer with no symbols for a consistent pop-up experience.

Map is Fast and Responsive

Tips

Use neutral gray for the most widely dominant population (in this case, white), and leave its layer off by default to let more interesting patterns be visible at first glance.

More Information

Map Author

Owen Evans

Owen Evans

@OwenGeo | LinkedIn

Web mapper@Esri, husband/dad, ice hockey fan, floor hockey player, dog owner, guitar strummer.

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