Cartography - Maps of North America and the USA

Cartography -

the Art of Making Maps, the Science of Where You Are

Maps of North America and the USA

Showing the Curvature of the Earth

We've zoomed down to view just North America in the GOES-6 image.

On a map of the corresponding area, we can put in more details since we are showing less of the Earth. In this map, rivers are blue; national borders, state borders (USA) and province borders (Canada) are brown.

Using the elliptical projection for the map produces a map that looks very much like the image. As you can see, the horizontal, East-West lines of latitude are parallel, but the North-South lines of longitude curve to meet at the poles. This can make it tricky to determine the directions.

For example, on this map, "north" depends on position. At the bottom left of the map, north is up and a little bit to the right. At the bottom right of the map, north is up and a little bit to the left.

Activity 1: North or South, East or West?

When we use a rectangular projection, the lines of longitude are parallel to each other and you can determine directions from one place to another. At every place on this map, "north" is straight up.

Answer the following questions:

The Hawaiian Islands are in the bottom row, second square from the left. Which is farther north: Hawaii or the northern border of Mexico?
Hudson bay is the large area of open water in eastern Canada. Is the western shore of Hudson's bay east or west of the western shore of the Gulf of Mexico?

What Grows Where?

This map of the continental United States uses color to show vegetation and shading to show topography - mountains and valleys. The vegetation data comes from processing data from special cameras on the AVHRR (Advanced Very High Resolution Radiometer) satellite. Vegetation reflects the green part of sunlight, as well as infrared, but does not reflect much of the other wavelengths. Water, soil, rock, roads, and buildings reflect sunlight differently. Scientists combine the amounts of reflected green, red, and infrared light to map vegetation. A map of land elevation is then added to show the topography. In this false color image, the amount of red (not green!) indicates what and how much is growing at a location.

Ground Cover	Color
Swamp	dark tones (mix of red and blue)
Grasslands	light red
Croplands	red
Deciduous trees	red
Coniferous forests	dark red or maroon
Deserts	white
Lakes and rivers	blue (deeper water is darker blue)
Exposed bedrock	dark bluish-green
Urban areas	bluish green

The information in this table comes from the image caption. Depending on your screen, some of these colors may be hard to see.

Activity 2: Reading the AVHRR Image

The small images in this table are all cut from the larger AVHRR image (558kb). Match each small AVHRR image (numbered 1 through 8) to the correct location description (lettered A through H).

Match Images to Locations
Small Image	Location Description
1.	A. The Great Salt Lake and the Great Salt Lake Desert in Utah
2.	B. New York City (on the Atlantic Coast)
3.	C. Mojave Desert in southern California
4.	D. Chicago, Illinois (on the southwest shore of Lake Michigan)
5.	E. The Mississippi River Delta in Louisiana (Can you also spot New Orleans and the surrounding communities?)
6.	F. Tall peaks in the Rocky Mountains (Hints: what is the treeline? what would snow look like on a vegetation map?)
7.	G. Cascade Range in Oregon and northern California (Look for the rain shadow effect: slopes are drier away from the direction of the prevailing weather path.)
8.	H. The Florida Everglades (Can you also see Miami, Fort Lauderdale and the nearby communities?)

Activity 3: Interpreting the AVHRR Image

For the table in Activity 2, use the images to describe the ground cover for each location.

A. The Great Salt Lake and the Great Salt Lake Desert in Utah
B. New York City
C. Mojave Desert in southern California
D. Chicago, Illinois
E. The Mississippi River Delta in Louisiana
F. Tall peaks in the Rocky Mountains
G. Cascade Range in Oregon and northern California
H. The Florida Everglades

Zoom down to Maps of Washington State.
Zoom back up to World Maps.

Image Credits

Line map - Xerox PARC Map Viewer allows you to view maps of any portion of the Earth. You can also use it to reproduce the rectangular projection map of North America.

Topographic map - Los Alamos National Laboratory presents an image derived from AVHRR data transmitted by NOAA's GOES-8 & 9 satellites.

Related Information

Written by: Rob Westcott, Hugh Anderson, and Lorraine Johnson.

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Last Modified Fri Jan 24 23:22:50 1997