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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.
Parts
- Mark — The core mark of Choropleth story maps is color of administrative regions mapped to a quantitative rate.
- Scale — The scale must show zero (or a declared break) and units.
- Axis — Axis titles name the variable, not a mood.
- Legend — A legend is weaker than a direct label. Write beside the mark when you can.
- Label — Numbers are optional. If comparison is the job, label the ends only.
- Grid — Keep the grid faint. Data should own the ink.
- Annotation — One annotation sentence. Date the source.
- Frame — A thin frame. Never a 3-D box.
Variants
- Filled region map — Variant 1 of Choropleth story maps (Filled region map). Same encoding, different layout.
- Rate map — Variant 2 of Choropleth story maps (Rate map). Same encoding, different layout.
- Area shading — Variant 3 of Choropleth story maps (Area shading). Same encoding, different layout.
- Choropleth story maps 4 — Variant 4 of Choropleth story maps (Choropleth story maps 4). Same encoding, different layout.
Labels
- Axis — On Choropleth story maps, make Mark readable.
- Legend — On Choropleth story maps, make Scale readable.
- Label — On Choropleth story maps, make Axis readable.
- Grid — On Choropleth story maps, make Legend readable.
- Annotation — On Choropleth story maps, make Label readable.
Choropleth story maps: honour color of administrative regions mapped to a quantitative rate, and switch when raw counts without normalizing by population or area.