MAPS
They really can be so much fun!
The United States of Food
DIFFERENCES AMONG THESE MAPS?
Map B
Map A
Map C
IMAGINE FOR A MOMENT…
1.
2.
…a globe made of glass
…a bright light in its center casting land shaped
shadows in all directions.
The cartographer’s job is to gather those
shadows and transform them into a reasonable
portrait of the planet…this is the art of
PROJECTION
PLANAR PROJECTIONS

Project the Earth onto a plane that touches—or,
technically, is tangent to—the globe at a single
point, and you get a planar projection. Because
this projection, also known as an azimuthal
projection, is most accurate at its center, it is
often used for maps focusing on one of the Poles.
CONIC PROJECTIONS

Cap the globe with a cone to achieve a conic
projection. Cut open the cone, and the basis of a
map emerges. The map will be least distorted
along the line where the cone touches the sphere.
Conic projections are handy for portraying the
United States, which fits nicely within the
resulting smile-shaped map.
CYLINDRICAL PROJECTIONS

Swaddle the globe and project its surface onto a
cylinder. Slit the cylinder and flatten it into a
map. This projection is most accurate near the
Equator and greatly distorted near the Poles. The
most famous cylindrical map is the Mercator
projection, perfect for navigation but poor for
teaching geography.
PRESERVING AREA

To compare geographical data on a level playing
field, pick a projection that maintains the correct
proportions among the sizes of Earth’s
landmasses. Such a map, often called an equalarea projection, would be useful to demographers.
The price of getting the sizes right, however, is
distortion in the shapes of the continents.
PRESERVING SHAPE

Preserving the shape of a landmass—an
important concern for those wanting to see what
Earth “really” looks like—gets harder as the area
covered gets larger. A world map can only
preserve the continents’ shapes by distorting
their sizes. Maps that stress shape are called
conformal.
PRESERVING DISTANCE

Geometry students the world over learn that the
shortest distance between two points is a line.
Not on most maps. If distance is the focus of your
map, choose a projection centered on a key point.
Lines radiating from the middle will be
equidistant. Shapes and sizes will be distorted,
however, especially at the outer edges.
PRESERVING DIRECTION

Many navigational charts rely on projections
focused on direction. Such maps, usually centered
on one place, allow mariners to plot a journey
they can actually sail without constant course
corrections. That ability matters far more at sea
than shapes and sizes, which can get distorted.
BEST FOR A WORLD MAP?
1922, National Geographic
adopted the Van der Grinten
projection, which encloses the
world in a circle.
 1988, switched to the
Robinson projection, on
which the high latitudes are
less distorted in size (but
more so in shape).
 1999, began using the Winkel
Tripel projection, which
provides a better balance
between size and shape.

CHOROPLETH MAPS

Features:

Progressive shading of regions to indicate degrees of
a topic
CARTOGRAM MAPS

Features:

A map which adjusts the sizes of countries so as to show
the relevance of a topic
IMAGE CREDITS
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US of Food: http://www.foodiggity.com/wpcontent/uploads/2011/01/food-by-state2.jpg
US of Soda: http://www.foodiggity.com/wpcontent/uploads/2011/01/united_states_of_soda.jpg
Coke-Soda-Pop: http://quittingsoda.com/wpcontent/uploads/2008/09/popvssodamap.gif
Black/Yellow Map Projections:
http://www.nationalgeographic.com/xpeditions/hall/1/x1/xpe
dition1.html
Quote image & various projections:
http://www.nationalgeographic.com/features/2000/explorati
on/projections/
Cloropleth: Rubenstein, James M. The Cultural Landscape: An
Introduction to Human Geography. 9th Ed. Upper Saddle River,
NJ: Pearson/Prentice Hall, 2008. CD-ROM.
Cartogram:
http://www.worldmapper.org/display.php?selected=219