Maps

Geography distorts data.

Area is not population

A choropleth map colours land, and land does not vote or buy things. Large empty regions dominate the visual impression regardless of how few people live there.

Population cartograms distort shape to represent people fairly.
Always map rates rather than counts.

Projections

Every flat map distorts area, shape or distance. Mercator enlarges high latitudes enormously, which shapes intuitions about country sizes.