Geography 222 The Power of Maps Geog 222 Main Page and Course Description Geog 222 Syllabus Geog 222 Course Schedule Geog 222 Exercises

Geog 222 Exercise 6: Census Atlas of Home

Revised: 3/26/11

ASSIGNED in class Monday March 28
DUE: Decision on scale of data and maps Monday March 28
DUE: in class Wednesday April 20 (w/required discussion) at 9:00 am


This exercise involves making and interpreting choropleth maps of U.S. Census data in the area around your U.S. home.

You will draw upon past lecture material about data classification and color symbolization (in the Cartographic Abstraction Lecture Notes) to complete this exercise. You will also be expected to interpret the patterns you see on the maps you create, based on what you know about your home.

Basic Information about the U.S. Census

The U.S. Census provides data aggregated to many different sized areas, the smallest area being the block level - usually an area about the size of a city block. In rural areas these "blocks" are larger in area (but they contain about the same amount of people as a city block). Some, but not all Census data is available at the block level. Different data is available at the Census Block Group level (the data from numerous blocks are aggregated into a larger area). The following graphics illustrate the hierarchy of census geographic entities, and are taken from the U.S. Census Geographic Reference Manual which has much more information about U.S. Census Geography if you are interested (which of course you are).

You already used the U.S. Census Bureau's American Factfinder to locate some quick facts about your home county, in exercise 4. We will use some more advanced mapping features of this site to create detailed maps of 2000 U.S. Census data in your home neighborhood. Unfortunately, the Census has not yet managed to get the new 2010 Census data into this mapping system.

Goals: You will map eight different Census data variables, around your home, and provide basic map reading, analysis, and interpretation of patterns on these choropleth maps.


If the Census mapping site is not working it may be because you have your browser set to block pop-up windows. Turn that feature off for this exercise!

Go to the Thematic Maps page at the US Census Bureau.

You should see a map of the US by state with Persons Per Square Mile: 2000 data.

You need to change the geographic area on the American Factfinder site: zoom into the area around your home. Changes in the area you are viewing and scale are called Geography.

1) The American Factfinder site offers different ways to change scale. For now do this...

2) Change the level of detail of the Census geography and data. From the pop-up menu near the top center of the page:

3) Change the scale, adjust the center of the map, or identify a particular census block:

You need to select a scale (such as 7 miles across) and level of detail (block level data) and create each of your eight maps at that scale and level of detail.

Please show the instructor your decision on the scale and detail (block level in most cases) of your map prior to proceeding with this exercise!

Now that you know how to change the geographic area shown on the American Factfinder site, you need to learn how to look at the different data variables the US Census collects. These data variables are called Themes.

3) The American Factfinder site offers different ways to change data themes. For now do this...

Now that you know how to change the theme and geographic area shown on the American Factfinder site, you need to learn how to adjust the Data Classification and what features are shown on your map. This can be accomplished by adjusting the Legend.

4) Click once on the word Data Classes on the upper left side of the screen. A new smaller window should pop up.

You now know how to change the theme and geographic area shown on the American Factfinder site, as well as how to adjust how your data is classified and what features are shown on your map. The American Factfinder site does more than this, but these are the basics you need to complete this exercise.

The ultimate goal of this exercise is to make a Census Atlas of Home using the American Factfinder site and the U.S. Census 2000 data. Before you begin this task, please do the following:

5) Generate 8 different maps of 8 Census themes for your Census Atlas of Home. Each should have the same scale and US Census data level (eg., Blocks) and each should have the same features (roads, rivers, etc.)

6) Finally: do some basic map reading, analysis, and interpretation for each map. This should be easy for most of you to do as you are familiar with the place - home - you have mapped.

Format your work like the following example (you should be able to fit each map with its associated reading, analysis, and interpretation on one page):

Percent Persons under 18 Yrs Old, U.S. Census, 2000

Map reading: process of determining what the map maker has depicted

ex) A choropleth map of the city of Waukesha, Wisconsin, showing the Percent of Persons under 18 years old, in 5 classes, classified by natural breaks.

Map analysis: process of seeing spatial patterns on the map

ex) In general, the further you move away from downtown Waukesha, the higher the percent of people under 18. Distinct low areas in the north-central part of town, and in a few blocks in the extreme south part of town, and directly south of downtown. Distinct high areas in the west, south-east, and north-east areas away from downtown. Mid-level areas in many of the areas surrounding downtown. The particular block where my parents live has a mid-level of persons under 18 years old.

Map interpretation: explaining the patterns noticed in the map analysis; note low areas, medium areas, and high areas; note things that surprised you and explain patterns based on what you know about your home.

ex) These patterns are explained in several ways. The general pattern of a higher percentage of people over 18 living in the areas away from downtown is easy to explain: more families with children live in the suburban areas of town, than live downtown. Specific very low blocks are areas that are not residential: some low blocks downtown are largely commercial and have few houses or apartments; some low blocks to the south of town are industrial parks, again with few places for anyone to live (looking at a map of general population in the area shows that few people live in these areas). High areas are explained by several factors: some are new subdivisions, which appeal to families with children. Also, the Census blocks around the three high schools in town have higher percentages of people under 18 - people with kids live near schools. I was surprised that there were relatively low numbers of under 18 persons in many of the older residential areas of Waukesha. This is probably because many of the homes in these areas - built in the 1960s - are owned by couples who's children, like myself, no longer live at home: empty nesters. It may be the case that these folks will sell their homes to young couples before the next Census, and these areas will show higher percentages of people under 18 in the 2010 Census as a result.

What is Due

Please turn in the following:

Remember that we will take some class time to discuss the results of this exercise on the day it is due. You will use these maps in your take home final exam.


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