Geospatial Mapping

Before you make a map, ask yourself: Does the geographic location actually matter to the narrative? If you are just comparing sales figures across 5 countries, a bar chart is vastly superior. Only use a map when spatial patterns (clustering, proximity) are the point.

Choropleth Maps

Regions (states, counties) are colored based on a data value. This is the most common map type, and the most frequently abused.

The Problem	The Solution
Area Bias	Large, sparsely populated regions dominate the map visually, while small, dense regions disappear. A map of the US always looks red because large western states vote Republican, even if the population is small. Use a Cartogram (where region size is distorted based on population) or a hex-tile map.
Absolute Numbers	Never map absolute numbers (e.g., "Total COVID Cases") on a choropleth, because it just becomes a population map. Always normalize the data (e.g., "Cases per 100,000 people").

Dot Density Maps

Instead of coloring a whole region, place dots within the region, where one dot represents a certain number of units. This fixes the area bias of choropleths.

Next Steps

If you don't actually need a map, go back to Comparisons and use a bar chart.