USA Population Change | Maps We Love

Why we love it

We love how colour and 3D shading work together to tell the story of US population changes from 2000 to 2010. Declining counties show up in red and shrink into the map. Growing counties pop in green and literally burst from the screen. As a bonus, you can zoom into a city to reveal more spatial details and discover changes in a particular neighborhood.

Why it works

What really makes this map useful (and smart) is the 3D shading compares nearby places using relative height. 3D especially showcases meaningful and even subtle differences within each colour. For example, red simply tells us places are shrinking in population, but shading gives us relative-depth cues to indicate wide differences in losses within that category.

Important steps

Select time period data

You will need population data for two different time periods such as 2000 and 2010.

Use diverging colour scheme

Map the data using a diverging colour scheme (known in ArcGIS Online as “above and below”), and make the middle colour neutral, centered on 0 or “no change.”

Creating 3D effects

Run a Python tool on Github to create 3D effects.

Add shadow effects for 3D

Evaluate and publish your map

Evaluate the results in ArcMap or ArcGIS Pro. Publish as a tiled map service to ArcGIS Online.

Requirements

Data and software

You need numerical data — it could be income, housing prices, life expectancy, anything that shows change over time. Maps like this work best with data that is a rate, ratio, percent, index, or average, and changes over time. Software used: ArcGIS Desktop, ArcGIS Online.

Analysis

Think about how to show growth and decline in population. Here, zero growth is a neutral colour and growth rates are shaded in diverging colors. The Python tool analyses growth rates to determine height and shading for each feature.