Population Growth & Decline

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Why We Love It

Population is so much more than numbers. Its growth drives demand for housing, jobs, food, education, transportation, and services. Its decline puts pressure on local business, government, housing, and people. We love how this map shows the growth/decline pattern and gives a sense of urban, suburban, and rural population density. It illustrates the story that most US cities are emptying out in an ever-expanding bubble called the suburbs.

Why It Works

This map could be used as a backdrop for any organization showing locations, services areas, or other subjects. It shows you population growth and decline in a clear light. Red areas will lose population by 2015, while green areas will grow. Darker green areas will grow more than 1.25 percent per year. You can click on the map for details about an area. There is also a simple app showing this web map. You can download the data from the map package.

Important Steps

Working within ArcMap, take any dataset containing a population count for two different years.

Add three new fields: Decline, Normal Growth (<1.25%), and High Growth (>1.25%).

Select all records where population change is > 1.25%.

For each field, calculate the number of people predicted to increase or decrease. Use this value to set the dot density renderer in ArcMap using each of the three columns. The map package MXD file uses a set of scale-dependent renderers to pattern from.

Requirements

Data

You will need numerical data to make a map that depicts change: The numeric difference between two time periods shows whether something is increasing or decreasing. You can use stronger colors to denote larger amounts of change.

Analysis

In each area, calculate the predicted increase or decrease in the number of people. Use this value to set the dot density renderer in ArcMap for each column (decrease, increase up to 1.25%, large increase > 1.25%).

Time

In ArcMap, it takes one hour to author the map, plus time to cache the results to a server or organization account.

Tip

Use a very light or very dark basemap when making dot density maps to help draw out the subtle patterns.

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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