Map reader

Every map answers some questions and hides others. Pick a map type and see one invented data set drawn six ways: a reference map, a choropleth, a dot density map, a graduated symbol map, an isoline map and a cartogram. Read the legend first, then name the pattern with a place, then say what the map cannot show.

All the values in this trainer are invented for practice, even on real outlines, and they change from problem to problem. Never quote them as facts about a real country.

How the maps are made

Outlines. The world and regional maps are drawn from Natural Earth public domain data (1:110m) in the Equal Earth projection, which keeps areas true. Borders follow Natural Earth’s de facto lines; they show no position on any disputed territory, and disputed places carry no value here. Country A is an invented country of eight provinces.

Values. Every value is invented: a trend toward one side of the map plus random noise, sorted into classes with equal numbers of places. Dots are placed at random inside each place in proportion to its count; circle AREA is proportional to the value; isolines are drawn bunched on one side so you can see fast and slow change. The cartogram resizes each province of Country A by its number of people.

Legible at 360 px. Every word (letters, line values, the legend) is text on the page, not inside the picture, and a checker draws 300 problems of each kind and refuses any map whose labels would touch on a phone.

Notes for this topic: Introduction to Maps