Basic Map Projections

AP Human Geography

Distortion and Projection

• All maps have distortion. Why?• Best projection? Depends on how you use the

map?

Mercator (1569)

• Designed to aid ships; good at finding location; bad at distortion of poles

Robinson Projection

• Good at fixing pole distortion; good for general use (common in classrooms)

Peters Projection (1974)

• Controversial; b/c distorts familiar land shapes• Corrects distortions of Africa and S. America

Types of Thematic Maps

• Dot Maps

Isoline

Choropleth

Cartogram

Proportional Symbol Map

Scale

• Displaying the same geographical features at various scales may also depict misleading results.

• For example….

Manipulating Data

• Data may also distort desired results. The following slides show how population of a particular cohort may be misleading.

NYC = Texas?

SO Cal = Texas?