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How to Tell a Story with a Map

Learn how to find patterns and interpret your map.

Peter Freeze avatar
Written by Peter Freeze
Updated over 10 months ago

When you’re working with geographic data, maps can help reveal patterns and tell a story. Some common patterns are:

  • Clusters,

  • Islands,

  • Alignment, and

  • Division.

Here's how to identify them on a map.

Finding Clusters on a Map

Clusters are groups of neighboring geographies with similar measurements.

  • How to spot clusters: Look for a group of areas on the map with similar data points.

  • What clusters can reveal:

    • Population enclaves with similar experiences

    • Populations that are being exposed to similar conditions, such as a high concentration of opportunity or disadvantage

Identifying Islands on a Map

Islands, or spatial outliers, are areas that don't fit the pattern within a cluster.

  • How to spot islands: Look for geographies within a cluster that have noticeably different measurements.

  • What islands can reveal:

    • Islands can highlight the presence of unique circumstances or factors affecting a specific area.

    • Using more data, your local knowledge, or community outreach, you can build an idea of what conditions may be different there.

Alignment of Two Variables on a Bivariate Map

Alignment occurs when two variables follow similar spatial patterns.

  • How to spot alignment: Look for neutral colors that show up in the center of a bivariate map legend.

    • On the yellow – blue scale, look for shades of gray.

    • On the magenta – green scale, look for shades of purple.

  • What alignment can reveal: Alignment helps show how two factors, like income and access to transit, relate across areas within a community.

Division of Two Variables on a Map

Division shows stark contrasts between geographies based on two variables.

  • How to spot division: Look for areas where strong colors represent extremes in a bivariate map.

    • For the yellow – blue scale, look for strong yellows or blues.

    • For the magenta – green scale, look for strong magentas or greens.

  • What division can reveal: Division tells a story of how different parts of a region may have been shaped by historical or social factors.

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