1. Steps toward cartographic literacy
MAPS & JUDGMENT
Steps toward
cartographic literacy

2. Projections
Every map employs some kind of projection to transform spherical surface to flat surface
Choice of projection reflects priorities of cartographer in regard to preserving one of the following (or compromising between all)
Area
Distance
Direction
Shape
Read the Introductory section in your atlas (this is required reading!)

3. Mercator projection
Why did my plane from Paris go so far out of the way to get to Chicago?

4. Mollweide Projection
Maybe it didn’t go too far out of the way…

5. Azimuthal projection (north pole)
That explains it!
Remember that every projection is a distortion.
How is this projection distorted?

6. Judgment is inevitable when making maps
All maps involve decision-making process
There is no “natural” way to draw a map
Maps are not reflections of reality but selections of reality
Maps can be analyzed and critiqued just like literature to determine what the cartographer believed and thought about the world, and his/her values, beliefs, objectives, etc. (J.B. Harley, John Pickles, etc.)

7. Who might have made this map and why?

8. Medieval “T&O” map
What common words in the English language reflect this tradition of mapping?
Orientation
Oriented

9. Thematic Maps
Thematic maps represent one or two variables (population, ethnicity, income, language, religion, etc.) in map form
The “language” of thematic maps is quite varied, and involves the use of color, shape, pattern, light and dark, etc.
Thematic maps serve two main purposes:
Analysis of data
Presentation of data

10. Map with pie chart callouts
What are the strengths and weaknesses of this cartographic language?

11. Choropleth map
What are the strengths and weaknesses of a choropleth map?

12. Cartogram and choropleth
A cartogram is a boundary map in which the areas are distorted systematically: every partition’s area shows its value for a particular variable

13. Isoline map of population
Why use an isoline map for population rather than a choropleth map?

14. Choropleth maps
From A to Z

15. Choropleth maps Tremendously common and useful
Use some existing system of boundaries (countries, states, counties, voting districts, etc.)
Group data into 2 or more levels or classes using slicing values
Show spatial variation of one or two variables at a time by using color, shades of grey and/or patterns

16. Percent of Population White (not Hispanic)

17. Percent of Population White (not Hispanic)

18. How can such different looking maps show the same variable?
Cartographic reasons
Different slicing values
Different levels of spatial aggregation
Geographical reasons
Uneven distribution of minorities at the state scale as well as at the national scale
Concentration of minorities in cities, particularly in northern states

19. Different ways of “slicing” data
The Data {42, 50, 55, 57, 61, 77, 79, 97}
Equal interval
Three classes based on range 40 to 100
{42, 50, 55, 57} {61, 77, 79} {97}
Quantile
Quartiles (lowest 1/4 of observations, next 1/4, …)
{42, 50} {55, 57} {61, 77} {79, 97}

20. Different ways of “slicing” data
Natural breaks
{ }
{42} {50, 55, 57, 61} {77, 79} {97}
Standard deviations
Mean = 64.75, Std. Dev. =

21. Natural Breaks

22. Equal Interval

23. Quintiles (quantiles based on division into 5 classes)

24. Which map would be preferred by each of the following users?
The ACLU
The KKK
A geographer studying the relationship between ethnicity and poverty
A spokesman for the Georgia branch of a charitable assistance association targeting minorities

25. Not very useful this way
Generally it helps to re-order the data

27. quartiles: what is 52 ÷ 4 ?
What if you wanted to use quintiles?

28. How informative would “natural breaks” be in this case?

29. Problems with choropleth maps
Make it easy to slant data to suit the cartographer’s purpose (by adjusting the slicing values)
Create the illusion of rapid breaks whereas data varies continuously and gradually in the real world
Allow small areas (like major cities) to overwhelm the data of large regions (like states)

30. Mapping inequality in Africa
Mapping economic inequality
Variable used: GINI index

31. GINI index measures economic inequality in a society
Country
Gini(%) 1
Algeria
35.33 2
Botswana
66.7 3
Burkina Faso
46.85 4
Burundi
42.39 5
Cameroon
46.82 6
Central african republic
61.33 7
Côte d'Ivoire
36.68 8
Egypt
30.33 9
Ethiopia
39.96 10
Gambia
50.23 11
Ghana
39.55 12
Kenya
44.93 13
Lesotho
63.13 14
Madagascar
38.11 15
Malawi
50.31 16
Mali
50.5 17
Mauritania
37.71 18
Morocco
39.46 19
Mozambique
39.61 20
Namibia
74.33 21
Niger
50.61 22
Nigeria
50.56 23
Rwanda
28.9 24
Senegal
41.28 25
Sierra leone
62.87 26
South africa
56.59 27
Swaziland
60.65 28
Tanzania
59.01 29
Tunisia
41.66 30
Uganda
37.4 31
Zambia
53.8 32
Zimbabwe
50.12
GINI index measures economic inequality in a society
100% = completely unequal
0% = completely equal

32. Can you identify the classification schemes?
Equal Interval
Quantiles (Quartiles)
32 entries ÷ 4 = 8
4 groups of 8

33. Can you identify an observation that “jumps” two classifications?

34. Can you think of a scenario with:
Two different map users (think in terms of organizations and professionals)
Opposite judgments of what is the “best” map for their purposes?
South Africa
South Africa

35. What would you guess… ?
Source: Wikimedia commons

36. How can you map a process?
Process Maps
How can you map a process?

37. Map with pie chart callouts
To see the process (growing American dominance in the movie theater) you have to visually compare each pair of pies

38. Expansion of the EU
To see the process (expansion of the EU) you have to know what color comes first, second, third, etc.

39. Religious diffusion
To see the process (religious diffusion) you must follow the arrows

40. Mei-Po Kwan
To see the process (human movement) you must follow the time-space path from the bottom of the lower blue line to the top of the upper blue line

41. Mei-Po Kwan

42. Paul Adams

43. Charles Joseph Minard’s map of the disastrous Napoleonic campaign in Russia (1812)

44. Questions Why use an isoline map instead of a choropleth map?
Why use a choropleth map instead of an isoline map?
What kind of map is unbiased?
What kind of map reflects the interests, intent, and biases of the mapmaker?
What are some problems with choropleth maps?
What are some processes that people have managed to map?
What are some cartographic ways of showing change through time?