C. The Choropleth Map
This map form shades the statistical areas according to the data values.
It is appropriate for percents, densities, and other ratios, but not for
counts of phenomena. Typically the data values are displayed in three to
seven classes. There are various strategies for deciding where to position
the class breaks within the distribution. Ideally you would have about
the same number of values in each class with no empty classes or classes
which end and begin with the same value. For example if you had a large
number of 0 values, some of them might be allocated to both the first and
second classes by the computer.
1. Create a new project named: US Mortality.
From the initial Projects window select the Table icon and select
Add.
Locate the dbf or ascii file containing the county FIPS codes, infant
mortality, median household income, percent in poverty, and any other variables
you may have included. If your table is text type, be sure to indicate
if you have labels in the first row. Remember that your table FIPS codes
must match exactly to the county FIPS codes in the ArcView county boundary
files. Pay particular attention to those states which have a leading 0
in their state code. For example, California is 06 not just 6. The code
for Los Angeles County would be 06037.
If there is a problem with your codes, use a spreadsheet like Excel
to correct the codes. Note that the codes should be character variables
and not numeric.
2. After your data table has been added, open a new View window.
3. From the View menu item select the Add Theme option.
4. Locate the ESRIdata directory, the USA subdirectory, and
the COUNTIES file.
5. Select the Counties theme and open its table of attributes by
clicking on the table icon.
When the attribute table opens (COUNTIES.dbf), note the structure of
the FIPS tract identifier. You must be able to match it in your data file
in order to make a map.
6. Make sure both data tables are visible.
7. First click on the top of the FIPS item in the data table
you created. The column label will turn gray. 
8. Next click on the FIPS item in the COUNTIES attribute table.
9. Select the Table menu and then the Join option.
The software will append the contents of your data table to the COUNTIES
table and your data table will disappear. Scroll across the COUNTIES table
to see the appended items. If the rows are empty, or the columns not present,
then the join items did not match.
10. Return to the View window and click on the Legend to open the
Legend Editor.
11. When the Legend Editor opens, select the Legend Type window and
drag down to Graduated Color.
The contents of the window will change and you will now be able to select
an item for mapping.
12. From the new Classification Field button, select your infant
mortality variable.
Select the Apply button at the bottom of the window.
In this example Infmortrat is plotted with the default classing method
and in shades of red. 
Recall from earlier in this exercise that you may change:
1. the classification method and number with the Classify...
button. You may manually adjust the values and labels by clicking on the
actual values shown in the table. Click on Value first, change it, and
then click in the Label area.
2. the colors by selecting the Color Ramps window or by
double clicking on the Symbol item and selecting a modified color from
the Symbol editor.
13. Always remember to click the Apply button to make the changes
visible on the map.
14. When the map appears make whatever adjustments to its scale,
position, and framing you wish. The final printed version will be created
from the Layout window in the next section. Use the zoom in icon to select
a part of the United States so that the counties will be more easily seen.
15. Before creating a layout you must establish the coordinate system
used for the map. In this case the coordinates are latitude and longitude
and you will use miles for scale units. Select the View menu and the Properties
option. When the window at right appears, set the Map Units to decimal
degrees and the Distance Units to Miles. 
If you donít set these values, ArcView will not be able to create a
bar scale later.
16. Return to the main menu shown right and select the Layout icon.
Then click New. 
17. The Layout window is used to compose a map. Elements from different
Views, Tables, and Charts may be positioned here.
18. Select the File menu and the Page Layout option to change the
dimensions of the page.
You place various elements on the Layout page by selecting one of the
icons shown right and dragging it across the page where you want something
displayed. The top icon is for createing a map space. The second for the
legend space. The third for a bar scale. The fourth for the north arrow.
The fifth for a chart. The sixth for a table and the seventh for graphic
objects. You may add type by selecting the T icon and clicking it on the
page where you wish the type to be placed.
19. Select the Map icon and drag a space on the Layout window. Remember
to save some space for the legend, a title, north arrow, and a scale.
(See the next page for an example of a finished Layout.)
When the View Frame Properties window appears (shown right) select
View1. Click OK.
20. Now select the Legend icon and drag a window where you want the
legend to appear.
21. Select the Bar scale icon and drag a bar scale across the location
where you want it positioned.
22. Do the same with the North arrow icon.
23. The Layout window at right shows the result of creating the various
map elements.
24. Add a title using the T tool. Click on the map where you wish
to enter the type and then enter the text into the Text window.
Remember that you can change fonts and other symbol qualities by selecting
the Window menu and the Show Symbol Window... option. This is important.
25. Print a copy of your map. Remember to check the balance
and contrast of the various elements. Check for misspelled words also.
26. If you would like to finish your map in a drawing program such
as Adobe Illustrator, select the File menu and the Export option. Save
your map as an Encapsulated Postscript file. (Not the New eps)
