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Quick answers
When should I pick Choropleth story maps?
When the story is: regional comparisons, civics assignments, territory KPIs.
When should I avoid Choropleth story maps?
Skip it in cases like: raw counts without normalizing by population or area.
Who invented or popularised it?
Baron Charles Dupin (1826); modern TopoJSON + D3 geo pipelines
What does it encode?
color of administrative regions mapped to a quantitative rate
Is it OK in ads?
Yes if one claim is visible at a glance in Meta, Google and retail print; otherwise link to a full figure.
Will a teacher accept it?
Yes for lab reports and poster boards if axes, units and a source line are present.
Choropleth story maps encodes values as color of administrative regions mapped to a quantitative rate. Baron Charles Dupin (1826); modern TopoJSON + D3 geo pipelines.
In reports, ads and assignments it fits regional comparisons, civics assignments, territory KPIs. Skip it when raw counts without normalizing by population or area.
Mistakes
- Failure modes 1 — raw counts without normalizing by population or area
- Failure modes 2 — 3-D pies and perspective bars
- Failure modes 3 — Dual axes that fake a correlation
- Failure modes 4 — Truncated axes that shout a small delta
- Failure modes 5 — Legend only, no direct labels
- Failure modes 6 — Missing source, unit or period
Fixes
- Fixes 1 — Return to regional comparisons, civics assignments, territory KPIs.
- Fixes 2 — Flat, one axis, direct labels.
- Fixes 3 — Color-blind-safe palette plus pattern.
- Fixes 4 — Rewrite the title as a claim and add a source line.
Choropleth story maps: honour color of administrative regions mapped to a quantitative rate, and switch when raw counts without normalizing by population or area.