Geo325: Business Geographics
Lesson 9 ~ Thematic Map Using ArcMap, Showing Major Roads Only

Lesson Overview. In this lesson you will create a thematic map of Chester County in ArcMap showing census tracts and a geocoded business location. We will then add a roads layer and symbolize the layer by the type of road. Only those roads where traffic is heavy, like major roads and interstates, will be shown.

Before You Begin. Create a folder on your storage disk. Name it Lesson9 or similar.

Part 1. Launch ArcMap, Add Data Layers

Start Arcmap. In the ArcMap window select A new empty map and click Ok. Add data by clicking File -> Add Data or use the Add Data button    on the toolbar. Add the census tract coverage (cctracts.shp) and the streets layer (ccstreets.shp) for Chester County under the folder C:\Geo325\SpatialData\.

Now add the geocoded layer that you created in Lesson 4: Geocoding In ArcMap. Click on Add Data, navigate to Lesson4 on your storage disk, click on your geocoded business locations in the list, and then select Add.

(*NOTE* - If your business locations do not show up in the list as an layer with the .shp extension, you'll have to geocode them again. Do that now and then proceed.)

Set the data frame to the UTM, NAD 1983, Zone 18N projection, as you learned in Lesson 4 and Lesson 6. This projection is more appropriate for southeastern Pennsylvania.

Create a thematic map using the Chester County Census Tracts Layer. (CCTRACTS). Use a graduated color symbology. Choose a field that relates to your business locations. For example, the map below maps restaurants so the author mapped numbers of households. Refer to Lesson 6 for a refresher on creating a graduated color thematic map in ArcMap.  Your map should now look something like the one below.

Part 2. Create Thematic Map Showing Categories

We'd like to show streets and roads, too, but showing every single street and road makes the map quite cluttered. Let's draw the streets but show only the major roads. Further, let's distinguish on our map interstates from major highways.

Double-click on the CCSTREET layer in your table of contents. The Layer Properties window opens up. Click on the Symbology tab. On the left side, click on Categories and select Unique values. In the Value Field drop-down, select the field TYPEROAD. Now click Add All Values. (See image).

Arcmap will now look through every entry under TYPEROAD in the data set and show us each unique value it finds. You should now have four types of roads, including interstates, major roads, arterials and local roads, something like this.

Uncheck the box that says all other values. Now click on symbol used for Interstate. Select a color and width that is appropriate for interstates. (Hint: the prepackaged style for either expressways or highways works well.) Change the symbol for major to the major roads style. Now click on the category Local. Select the Remove option. We don't wish to show those roads. Remove Township roads from the categories as well.

As with layer names, we also want the category labels to be user friendly. Click on Interstate under the "Label" column. Edit that (by typing) to say Interstates. Similarly edit Major to say Major Roads. Now your categories are as follows.

Click Ok.

Once you click Ok, you should have a map that shows only major roads and interstates. The interstates will be drawn in a different symbol than the major roads. You now have another piece of information that will help you make a better business decision. In addition to demographic information, you can now consider how your customers can get to your business, and whether lots of people might be driving by!

We're just about ready to create a layout. Before leaving our data view let's tidy things up. Rename your layers so they are user friendly. Click on the layer you wish to rename. Right-click on the layer name and select Properties. Select the General tab, and then type in the name you want for this layer. Make sure the layer name shows what is displayed and uses proper English, not "computer-speak." For example, the CCTRACTS layer name should be changed to Census Tracts. CCSTREETS should say Streets, or Major Roads and Interstates. Make the text user friendly and then click Ok.

Label several of your geocoded locations as discussed in here in Lesson 4.

Part 3. Create Your Layout and Print

Click on View -> Layout View.

Create a new map layout as we have in previous lessons by following these steps:

• Set your page size to 8.5 x 11. Choose a landscape orientation.
• Make your map frame larger on the page. Select the frame; resize it and move it into position toward the left.
• Add a legend. Move the legend by clicking on it and dragging it to the lower right corner of the map.
• Add a scale bar  Right-click on the scale bar, select properties, and then make sure the division units are set to feet or miles, not meters.
• Add a north arrow  Move and resize the north arrow and scale bar accordingly so it fits above the legend.
• Add a title for the Map, click Insert on the menu and select Title. In the text box that opens type an appropriate title for the map.
• Add text for your name, class, date, and lesson number that will finalize the layout for printing. Click Insert on the menu and select Text. In the text box that opens type your name, lesson number, date and class section.
• Add a neatline. Click Insert on the menu, select Neatline and select Place inside margins for your placement. For the gap between the margin and your border select a 2 pt gap. Click Ok.
  

Print your map!

Save your work. Click on File in the menu bar, then go to Save As. Navigate to the lesson folder on your storage disk, type a project name in the File Name box (e.g., majorroads.mxd) then click OK.

Lesson documentation updated 08/01/07; Ellen Bryson.
The Center for Geographic Information Systems and Spatial Analysis at West Chester University