Cartogram

A cartogram (also called a value-area map or an anamorphic map, the latter common among German-speakers) is a type of thematic map where the geographic size of areas (like countries or provinces) is distorted to reflect a specific variable, such as population, GDP, or travel time. This makes it easier to visualize data patterns.

Types

1. Contiguous Cartograms – Shapes are distorted, but areas remain connected.
2. Non-contiguous Cartograms – Shapes maintain their form but are resized and may be separated.
3. Diagrammatic Cartograms – Replace areas with simple geometric shapes (circles, squares).
4. Mosaic Cartograms – Divide areas into small equal-sized units, like hexagons or squares.
5. Linear Cartograms – Adjust the length of lines to represent variables like travel time.

History

• The first cartogram was made in 1876 by Pierre Émile Levasseur, using squares to represent European countries by population, economy, and religion.
• Hermann Haack and Hugo Weichel (1898) created the first contiguous cartogram in Germany.
• Waldo Tobler (1963) developed one of the first computer algorithms for cartograms.

Uses

• They make it easier to compare values visually.
• They highlight regional differences more clearly than standard maps.
• Commonly used in election results, economic data, and population distribution maps.