2012 US Minority Population

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 colour 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 layer

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

Access county map layers

Show location as a symbol

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

Emphasise values

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

Copy the layer using different colours

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

Copy and configure

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

Save and share

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

Requirements

Data and software

The county map layer data was used. Software used: ArcGIS Online.

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-colour 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.

Tips and tricks

Keep colour ramp settings the same

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

Make your map colourful

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

Enable layer toggling

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.

Use neutral colours for dominant populations

Use neutral grey 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.