1. Introduction to ArcMap
Open the program by clicking on the Start Menu, then Programs | ArcGIS | ArcMap.
The ArcMAP Interface
Toolbars can be moved around in ArcMap. If the toolbar you need is missing, go to: View | Toolbars OR right-click on a gray area at the top, right corner of the screen. A list of toolbars will pop up, you can select the one you need from here.
Saving Your Work
ArcMap files are saved as .mxd files. Note that the actual data, the shapefiles and database files, are independent of this project. These files must be saved to your disk as well.
To save your work, choose File | Save As. Give your project an appropriate name, and save multiple copies of your work as you go.
2. Add Data
Press the Add Data button . Do you remember where you stored the data for this project? Use the menu to navigate to the appropriate folder. You will have to connect to your USB drive. Use the Connect to Folder button shown below:
Select the file called States.shp (this is a polygon shapefile) and press Add. After you have added the data, a map of the U.S will appear in the display window. It should look like the graphic below (or could be a different color). Notice also that you have a new item in your data layers menu (left). Click on the checkmark to make the states invisible. Click again to make the states reappear. This is called, "turning on and off a map layer."
You may also double-click on the box bellow the layer name (this one is light pink). A menu pops up that will allow you to change the color, or symbol, of your data layer.
Now let's add all the other shapefiles we will use for this project. Click on the add data button and again browse to the appropriate folder. You can choose datasets individually from a file list and add them to a map layout by holding down the ctrl key. Hold down the ctrl button and select Cities.shp and Rivers.shp. Click Add.
When multiple layers are added to an ArcMap document, layers are "stacked" one on top of the other in the data frame. This means that the layer listed at the bottom is in fact displayed underneath all other layers. Likewise, the layer listed first is on top of all other layers. To change the order, simply click on a layer and drag it into the desired position.
3. Projecting Data
Now we need to apply a projection to our map layout. We are going to project all three of our layers at once. We will project the data "on the fly" by using the Data Frame Properties dialog box. At the top of the screen select the View from the drop down menu then click on Data Frame Properties. There are a number of tabs on the Data Frame Properties dialog box, but for now we want to select the Cordinate System tab (see image below) .
Now we need to choose a coordinate system for our map. We want to choose a cordinate system that is custom for North America and we also want something that will keep areas equal across the entire map. Albers Equal Area Conic is a good choice for this map. To apply this coordinate system in the bottom half of the Coordinate System tab click on Predefined (this means we are going to choose a coordiante system that has already been defined). Next Click on Projected Coordinate Systems. Now click on Continental and then North American and finally click on USA Contiguous Albers Equal Area Conic Then Click Apply.
After clicking apply you will get a warning that looks like this:
Here is what your newly projected map should look like.
4. Changing the Map Symbology
To change the symbology, right-click the States data layer and choose Properties. Next, select the Symbology tab.
As you can see, all of the features (states) are currently being represented using the same symbol. You may click on the symbol to change it. You may also represent the features using other methods such as: unique values (under categories) and graduated colors (under quantities). You will learn about symbology selection and proper classification methods in class. Here it is simply noted that these options are available using this menu.
Example: Mapping Population Density
Population density is defined by the total population of a unit divided by the unit area. In this case, I will map the population densities for each state using the fields: POP1990 and AREA. This will be a graduated color map. Examine the following settings:
Hint: Normalization also means "divide."
Here is the resulting population density map:
Does the map appear how you would expect?
Notice the legend that now appears under the usastates data layer. Each category is represented by its own symbol. Symbols and labels may be changed in the data layer window. Left-click once on the label (it will highlight), pause, then click one more time. A cursor will appear, and you can edit how the category is labeled. For example: 1) use Low, Moderate, High or a meaningful word to describe the data instead of numeric values; 2) round numbers to a consistent decimal place or eliminate decimals all together.
Labels may also be changed in the Properties | Symbology menu. One click on the label will allow you to edit the text. This will be important when you are ready to make the final layout of your map.
Example: Mapping Graduated Symbols
A graduated symbol map varies the size of the symbol in proportion to the quantities that symbol represents. In this case, I will map the population densities for each city using the field: POP1990. This will be a graduated symbol. Examine the following settings:
(Note that we do not need to normalize in this instance.) Here is the resulting population density map:
How useful is this map? What are some of the trends that you see? What are some of the limitations of this map? How could these limitations be overcome? Can you think of some ways that we could normailze the data to convey a different message with our map?
5. Attribute Tables
To view the attribute table associated with the Cities shapefile, right-click the Cities layer in the left corner of your screen.
Choose Open Attribute Table from the menu. You will see a table open in a new window, like this.
Closely examine the contents of this table.
Next we will add the database file CityRanks.dbf to the ArcMap project. Use the Add Data button (as in the previous step) to navigate to this file. Once added to the project, we will see the table icon appear in the list of data layers on the left-hand side of the screen. Notice that you are now viewing the data sources (or directory) of layers rather than how the layers are displayed. Toggle between the two tabs at the bottom of the data layer menu (bottom left corner) to see the difference.
To view the contents of the CityRanks.dbf file, right-click the layer name next to the table icon and choose Open from the menu.
Closely examine the contents of this table as well. Notice that this file contains more information related to city data than the previous attribute table.
It is important to remember the difference between an attribute table and a database file. Both terms describe tables, yet they are stored in different formats. An attribute table is data associated with a shapefile or the geographic information necessary to display the map features. An attribute table will always contain fields that describe the shape (such as point, line, or polygon) or spatial coordinates of features. A database file does not necessarily contain this spatial information, and is not associated with a shapefile by default.
An attribute table may also contain other data, such as demographic or census data, or it may not. It may be up to you to gather the information you need for your analysis. If you wish to add information to the attribute table, you may do so using a database file. You may have worked with database files previously using Microsoft Excel. A database file may contain any variety of information that you wish to display and query using the GIS. In order to associate this data with the attribute table (or the shapefile/geographic information), you must join the database file to the attribute table. Once a join has been performed, the information in the database file is now linked to the shapefile. You can then perform queries and map features based on the "new" attributes, or the data added from the database file.
6. Joining Tables
For this project, we want to combine the election data in the CityRank.dbf database file to the attribute table associated with the shapefile Cities.shp. In order to perform the join, we must first identify a common field between the two tables. In other words, we must have one column of information in the attribute table that is EXACTLY the same in the database file. This is necessary for the data to be correctly associated with each feature, or row. Sometimes a numerical code is used for this common field, such as FIPS code. For this join, we will use a common field called STATE_CITY.
To join these tables, right-click the cities data layer and select Joins and Relates | Join from the menu.
Set up the join using the following settings.
Choose OK to finish the join. When asked if you would like to create an index select yes.
Now reopen the Cities attribute table. You will notice that the city rank and size data from the database file has now been added to the Cities attribute table. Look at the column names for further verification. You will see that columns originating from the attribute table are headed by Cities.xxxx (followed by the name of the field/column) and columns from the database file are headed CityRanks.xxxx. This helps you keep track of where your data is coming from.
If you made a mistake during the join, this is no problem. Simply right-click the Cities layer, and choose Joins and Relates | Remove Joins | CityRanks. This will undo the join, and you can try again.
7. Exporting Joined Tables
Now we have joined our data and have statehood information associated with our states layer and size/rank data associated with cities layer. Before we proceed lets export the datsets as new shapefile so that the appended data will be permanantly joined into individual shapefiles. This will make our tables easier to read, query and classify.
Right Click on the Cities shapefile and choose Data | Export Data.
Export the data using the following settings:
When prompted add the data to the view as a new layer.
Now let's take a look at the attribute table to make sure the data was exported correctly. Open the attribute table for Cities_wRanks and make sure that it contains the attributes of size rank from 1790-1990.
Repeat the above steps to export the States shapefile. Call the new shapefile States_wStateshood and save it into the same folder on your memory stick where you have saved all the other files for this project. Add the layer to the view when prompted and examine the attribute table. When you scroll across the attribute table you should see that the year the state entered the union is now the last listed attribute.
Now you can remove your original files from the table of contents since you do not need them anymore. Right click on the Cities shapefile and select Remove.
Repeat the previous step and remove the States shapefile as well.
8. Creating a Layout
Switch from Data View to Layout View using this toolbar: (bottom left).
The usastates map will appear on a layout page with the same settings as in the Data View (or the globe, the arrows mean "refresh"). You may make changes to the map and go back and forth between these views as you wish. Remember to use the Layout Toolbar (see Intro to ArcMap section) when zooming around in Layout View.
When creating a layout, the first step is to choose a page orientation. Go to File | Page Setup and select either Portrait or Landscape under Page Orientation.
Adding an Inset Map
At this time period the Northeastern part of the United States was densely populated. We must create an inset map so that we can see this region of the US more clearly. The first step in making an inset map is inserting a new dataframe. We need to be in the Data View so click on the Data View button (or globe). Let's give our exisitng dataframe a more meaningful name. You do this the same way you change any of the labels in the Table of Contents, just do a slow double click on the text you wish to rename (just like renaming a file in Windows Explorer). In your city rank project use a slow double click to select the dataframe Layers in the Table of Contents. When the word is highlited backspace and label this dataframe Main Map. Press Enter to finalize the new name.
Now we can insert our new Dataframe. Go to Insert| New Data Frame.
A new Data Frame will appear. Rename this Data Frame call it Inset Map.
Now we need to copy the layers from our exisiting Data Frame (Main Map) and paste them into Inset Map. Select the three layers in the Main Map Data Frame: Cities, Rivers, and States. (Note: you may have renamed these layers at some point). Once they are selected Right Click on one of the files and select Copy. Now Right Click in the table of contents on the words: Inset Map. Now select Paste.
Do you have an inset map in your layout? Click on the Layout View button to make sure. Your inset map should appear in your layout like this:
Use the Select Elements Arrow (from the layout toolbar): to position the inset map. Then use the zooming tools from the Standard Toolbar to zoom into your desired area of interest for your inset map.
You may wish to add a data extent rectangle to your main map. To do this Select the Main Map in the Layout View. Select View | Data Frame Properties.
Select the Extent Rectangles Tab and Click on the word Inset Map in the "other data frames" window. Now Select the Arrow to the right of the word inset map to move it to the "show extent rectangle for these data frames" window.
To format the extent rectangle Click on the word Frame. A Frame Properties dialogue box will appear. Apply the desired format options. To dismiss the box by Click OK. Then dismiss the View Properties click OK.
Next, add the map elements. Go to Insert and select Title, Text, Legend, Neatline, North Arrow, or Scale Bar as needed. Wizards will guide you through the setup and selection process. See below for an example.
You can also use the Drawing Tools (bottom toolbar) to add objects to the layout. These functions are very similar to Microsoft Word.
For precision alignment, use the Snap to Grid feature. Go to Tools | Options | Layout View. Make the grid spacing smaller, and check Snap elements to | Grid.
After you have added the map elements to the layout, you may make changes to them. Double-click on any map element to modify the font, line sizing, legend settings, or scale bar/north arrow selection. Experiment with different settings (sizes, colors, and positioning) to ensure that your layout has good visual balance.
And don't forget to include the cartographer's name!
9. Selection Methods
Selection tools allow you to isolate features of interest within the dataset. You may choose to explore different spatial or statistical relationships within your selection, or simply choose to represent a selection using different symbols. Features may be selected one of three ways using ArcMap: 1) Interactive Selection (using your mouse as a pointer); 2) Select by Attribute (or query attributes); and 3) Select by Location.
At the top of the screen you will see the Selection menu. This menu gives you the following options: Select by Attributes, Select by Location, Zoom to Selected Features, Statistics, Set Selectable Layers, Clear Selected Features, Interactive Selection Method, and Options.
When using the Interactive Selection Method, the first step is to set the selection method. Depending on the method you choose, each click of the mouse will either create a new selection, add to the current selection, remove from the current selection, or select from within the current selection.
After choosing a method, use the Select Feature tool found in the toolbar and left-click on a feature of interest. In this example, you will see that a state is highlighted, or outlined in cyan.
Note: The ArcMap Selection tool is set on "Create New Selection" by default. If you wish to quickly add to a selection, or select more than one feature at a time, hold down the shift key while pressing your mouse button. You may select as many features as you like using this method. If you release the shift key and click again, you will lose the selection.
Select by Attributes
This method allows you to select features based on a desired attribute or range of attribute values. The Select by Attributes menu allows you to perform the query two ways. The first is using the SQL calculator.
For this example, I decided to use the Select by Attributes tool to identify the cities with a population over 500,000 in 1940. To query for this information, I used the SQL calculator as shown below. The selected states shown in the map on the right match this criteria.
You can also query attributes using the Query Wizard (upper right on the menu above). This wizard walks you through the query process step-by-step and is useful if the SQL functions are a bit confusing to you. (If you keep getting error messages, try using the wizard.)
Select by Location
This method of selection is useful when you want to identify features within a defined spatial relationship. For this project, you will probably not select features based on location, but it is a very handy ArcMap tool that is worth knowing about. Take a bit of time to explore the options in this menu.
Saving a Selection as a Layer File
Once you have created a selection you want to keep, the next step is to create a layer or a shapefile from the selected features. This makes the selection more permanent. You can then modify the symbology, turn the data on and off as needed, or add it to a different ArcMap (.mxd) file.
To create a layer file, right-click the usastates data layer after you have finished your selection. Choose Selection | Create Layer from Selected Features.
A new layer file will be added to the data layer window. You can change the symbology and the layer placement as you wish. This is only a temporary setting, however. If you wish to make this layer more permanent, right-click the new layer and choose Save As Layer File. Select an appropriate location to store the file, and click OK.
To create a shapefile, right-click the usastates data layer after you have finished your selection and choose Data | Export Data. In the menu, choose to export the selected features using the same coordinate system as the layer's source data. Select an appropriate location to store the file, and click OK.
What is the difference between a shapefile (.shp) and a layer file (.lyr)?
A shapefile is a geographic map, containing all the spatial information needed to display this data. A layer file is comprised of data linked to places on the shapefile (or the usastates.shp). Both files types will work for this project.
Last revised 2005.09.22 firstname.lastname@example.org