Objective: In this lab, you will extract all Nebraska counties from the USA county shapefile, save Nebraska counties as a Geodatabase, and produce a population density map of Nebraska counties.
Creating a Geodatabase:
First we have to create the Geodatabase, open ArcMap in the usual way, creating
a New Empty Map, and click the ArcCatalog Icon or go under
Tools-ArcCatalog. ArcCatalog will open, and look like below.
There will be two columns, the first has Catalog at the top, the second
has three tabs: Contents, Preview, Metadata. In the first column navigate
to
where you want the Geodatabase to be. Then go under File-New-Personal
Geodatabase. In the second column the Geodatabase will appear.
You will need to name it. The name can be whatever you want it to be. Now
that the Geodatabase is created you can extract the Nebraska County Map.
Nebraska counties extraction.
Close ArcCatalog and return to ArcMap. When ArcMap is active add data by
going under File – Add Data. The location of the file you will need is
in c:\esri\esridata\usa. Click on counties.shp. Your screen should
now look like the following image representing all US counties:
Next, we have to extract just Nebraska counties. Nebraska counties all have a
state fips number of 31. We will use this number to select all
Nebraska counties by searching with an SQL expression. Click Selection
and then Select By Attribute, this can also be done by opening the
attribute table and under Options choosing Select by Attributes.
As you can see the layer indicates Counties since this is the only layer we have
added. There are the database fields on the left side of the Select By
Attribute window, mathematical operators in the middle and unique values at
the right side of the window. Now we will build a simple query to select all
counties where the state fips number equals 31. Double click
State_fips in the Fields column. It will appear in the lower part of the
query window. Choose equals (=) operator from the middle section. Then,
type in ‘31’, make sure you include the ‘’. Clicking Verify
will tell if you the operation executes successfully, after insuring it executes
click Apply and close the window. Your final query should looks like
this:
Exporting to a Geodatabase.
Once the query is executed all Nebraska counties will be selected. Now we have
to export the selected features. Right click the COUNTIES layer, point to
Data, and choose Export Data. Click the Folder Icon and
a new screen will appear. Make sure you change it to Personal Geodatabase
under Save as Type. Navigate to where your Geodatabase is located
and double click it. This will enable you to save into the Geodatabase.
Choose an export Name like Nebraska Counties which will become the name
of your new data layer you are going to create. Click Save. Make sure that Export Selected Features is selected
and Use the same Coordinate System as this layer’s source data is
checked, then click OK. When asked if you want to add the exported data
to the map as a layer, click Yes. The new layer will be added to your
project. You can switch off your COUNTIES layer or you can also delete it by
right clicking on COUNTIES and choosing Remove. If your map of
Nebraska is tiny, zoom in to see it at a reasonable size. Your view should now
look like this:
Assigning the correct projection.
Unfortunately this map is not in the correct projection. Right click on Layers in the Legend and click
Properties. The Data Frame Properties window will pop up. Click the
Coordinate System tab. Double click Predefined. Choose Projected
Coordinate Systems, then Continental, then North American and
finally choose USA Contiguous Albers Equal Area Conic. Hit OK. A
warning may pop up, go ahead and click Yes to proceed. Remember to save
your project occasionally. The Nebraska county map will appear in the correct
projection:
Working with the map.
Now we will prepare a population density map of Nebraska. Right click on
Nebraska Counties in the legend and open up Properties. Click on the
Symbology tab, then highlight Quantities in the left column and
choose Graduated Color. The map will be classified using the population
from 1999, therefore under Value select POP1999. In order to find
the population density of Nebraska, we need to select Normalization and
choose Area. Click Apply to see the effect in your graphic
window:
Next change the classes to 6 in the Classification window to see
greater diversification. To change the name of the layer, you have to click on the
General tab and type in the new title of the layer (Population Density)
in the Layer Name box. Click OK in the Layer Properties window. Finally we have to produce a map of the selected data.
Go to your Layout View and make sure the page setup is Landscape
for Map Size and Printer Setup. You will need to add a title, legend, neat
line, scale bar, caption, name and date to the map using Insert on the
toolbox. Your final map should look similar to this:
Map export.
Finally we will export the map as a .pdf. Choose File-Export Map
from the main menu. The export window will show up. From Save as Type
choose .pdf Name the file popdens
Save the file as popdens.pdf and move/copy it into your folder on Maps.
Part 2
ArcView U.S. Subregions merging Lab
Objective: In this lab we have to create a map of U.S. Subregions from the map U.S. States. As well as, save it as an independent file. During the final stage, we have to produce a population density map of U.S. Subregions.
Create a Geodatabase:
Create a Geodatabase the same way as before but name it Subregions.
Opening file.
Open ArcMap. In the ArcMap window make sure A New Empty Map is chosen and click OK. Go ahead and add states.shp from C:\esri\esridata\usa\.
Assigning the correct projection.
Unfortunately this map is not in correct projection. Right click on Layers in the Legend and click Properties. The Data Frame Properties window will pop up. Click the Coordinate System tab. Double click Predefined. Choose Projected Coordinate Systems, then Continental, then North American and finally choose USA Contiguous Albers Equal Area Conic. Hit OK. A warning may pop up, go ahead and click Yes to proceed.
Dissolving Features.
Features with the same value combinations for the specified fields will be aggregated (dissolved) into a single feature. This are in our case the sub regions of the United States. Open the ArcToolbox and double click on Data Management Tools > Generalization > Dissolve. Load the STATES layer into the Input Feature box via the dropdown menu. Next, browse into your Subregions database (Subregions.mdb) you created at the beginning. Name the output file subregions.shp (you need the *.shp ending) and click Save. Select Sub_Region for the attribute that you will dissolve in the Dissove_Fields box. Because you're dissolving the boundary between adjacent features, you need to decide how you want to combine their attributes. For this you need to choose AREA from the Statistics Field(s) dropdown menu and SUM from the dropdown menu which appears when you click in the white box next to the just chosen SUM. Repeat these two steps and add POP1999 and SUM to the second row. Finally, click OK and your sub regions layer will be created.
Now you can delete STATES.shp. Right click on States.shp and choose Remove.
Creating a population density map.
As in the Part 1, we will create a population density map. Right click on subregions in the legend and open up Properties. Click on the Symbology tab, then highlight Quantities in the left column and choose Graduated Color. The map will be classified using the population from 1999, therefore under Value select Sum_POP1999. In order to find the population density, we need to select Normalization and choose Sum_AREA. Choose Apply to see the effect in your graphic window.
Working with layout.
Finally we have to produce a map of the selected phenomena. Before doing that, right click on subregions and open up Properties. Click on the General tab and change the Layer Name to Population Density in US Subregions. This will also appear as name of the legend in the layout window. Open up your Layout view and make sure everything is Landscaped. Using Insert add all relevant items to the map: title, scale, etc…
Exporting the map.
Export the map as a .pdf, save on your disk and export to your webfolder.
Submitted by: Deborah L. Woracek, 2 November 2000. Updated by: Kristie
Raymond, September 2002, further updated by Eva Grund, August 2004