Tell a Story with a Map

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.