Map Projections & Types of maps AP Human Geography

Map projections

Map projections Cartographers have to deal with the problem of making maps of a spherical earth onto a flat surface  this leads to distortions Shape can be distorted Distance between two points can increase or decrease Relative size may be altered, areas can appear much larger than they really are Direction can be distorted

Robinson projection

Robinson projection More accurately shows the area near the poles Used to show proportions of land to water Distorts cardinal directions and distance

Mercator projection Used primarily for navigation since it is easiest to plot direction Increased distortion the further away from the equator Makes the North look much larger

Gall-peters projection

Gall-peters projection Focuses more on land area accuracy Released in 1974, based off a 1800 design More accurately shows southern hemisphere as larger than northern hemisphere Areas near the poles are stretched horizontally

Goode Homolosine projection

Dymaxion projection

Types of maps

Maps as a tool to understand spatial patterns Maps can give insight to how a phenomenon is occurring and provide the starting point for understanding the why Example: A doctor figures out why a group of specific people are getting cholera by using a map to see they were all living in the same general area and using the same water pumps, which were causing the cholera outbreak

Choropleth maps A map showing quantity by area. It uses shades of colors to show intervals

Isoline maps A map that is used to display distributions. It consists of lines that connect to show equal value

Proportional (graduated) circle maps

Dot maps

Caution: maps can be deceiving! Every map is flawed in some way Cartographers can be wrong, include inaccurate data, or make you perceive something differently that they want you to see by distorting the map

Glancing at that map, we’d think California, Texas, Florida, and New York were horribly dangerous places to live The problem is that we’re basically looking at a map of population. Of course the more people live in a place, the more crimes (all else being equal) will be committed there

These maps, from ads for Verizon Wireless, show 3G network coverage by Verizon and AT&T. The impression they give is that most of the US isn’t covered by AT&T at all BUT if you look at the map of population density, you will see that areas with the most people are covered