Skip To Content

Map homelessness by state

In the previous lesson, you published a layer of the United States with data on total population, homeless population, and change in homeless population. In this lesson, you'll use that layer to create three web maps of the United States.

Start a new map

Your first map will show the total number of homeless people per state. From looking at the data, you know North Dakota has a relatively low total number of homeless, so this map probably won't help your cause. However, because it's such a fundamental statistic, you must show it.

  1. Sign in to your ArcGIS organizational account.
  2. At the top of your organization's home page, click Content.

    Content

    The My Content tab on the content page includes two items titled Homelessness_yourname. One is a service definition that contains the actual data and drawing specifications for your published service, while the other is a feature layer that you can add to a map. You'll work with the feature layer.

  3. Click the ellipsis next to the Homelessness_yourname feature layer and choose Add to new map.

    Add to new map

    A new map containing the layer opens.

    Default map

    Note:

    Your default extent may differ from the above image depending on your monitor size and resolution. The symbology may look different than the map above, but you will change this.

    The current extent includes Alaska and Hawaii, so most of the states together only take up a quarter of the screen. Some of the smaller states are difficult to see at all.

  4. Zoom in until the extent roughly corresponds with the contiguous 48 states.

    Zoomed map

    Next, you'll rename the layer to reflect the data this map will show.

  5. If necessary, close the Change Style pane (click Cancel).
  6. In the Contents pane, point to the Homelessness yourname layer. Click the More Options button and choose Rename.

    Rename

  7. Rename the layer Homeless Counts and click OK.

Symbolize the layer by homeless population

Next, you'll symbolize the number of homeless by drawing a circle within each state. The size of the circle will vary depending on the attribute value. Using graduated symbols instead of colors helps the user compare symbols to one another independently of the areal boundaries of the states. It also avoids creating the impression that homeless people are evenly dispersed throughout each state.

  1. Under the Homeless Counts layer, click the Change Style button.
  2. In the Change Style pane, for Choose an attribute to show, choose Homeless Count (2013).

    Choose an attribute to show

    The pane updates to show the ways the attribute can be symbolized.

  3. Under Counts and Amounts (Size), click Select.

    Select button for Counts and Amounts (Size) drawing style

    The symbology on the map changes. Each state is symbolized with an orange circle that changes size depending on the state's homeless population.

    Default style

  4. Under Counts and Amounts (Size), click Options.

    Change Style options

    The Change Style pane changes to show the options. You can adjust symbol size, color, and more.

  5. Under Size, check Classify Data.

    Classify Data

    Classify Data uses a mathematical formula to determine the values at which symbols change size on the map, also known as breaks. The default classification scheme is Natural Breaks, which uses large differences between groups of values to set breaks.

  6. Under Classify Data, change the number of classes to 5.

    Five classes

    The number of classes determines the number of breaks in the data. When you change the classes, the symbols on the map update automatically. Many of the symbols are unnecessarily large and cover smaller symbols, so next you'll change the maximum and minimum symbol sizes.

  7. Under Size, change Max to 24 pixels and Min to 8 pixels.

    Style size

    You can also change the symbol color.

  8. Click Symbols.

    Symbols

    A window appears with additional symbology options.

  9. At the top of the window, click Fill. On the color palette, click the fourth dark blue from the top.

    Blue fill

  10. At the top of the window, click Outline. On the color palette, click the fifth dark blue from the top.

    Blue outline

  11. Change Line Width to 2 pixels.

    Line Width

  12. Click OK. At the bottom of the Change Style pane, click OK and click Done.

    Count map
    Note:

    The size of the symbols remains the same when you zoom in and out. Your symbols may appear larger or smaller relative to the state boundaries depending on your extent. You can change the symbol sizes in the Change Symbol window.

    In the above image, you can see that North Dakota and many of the rural plains states have small homeless populations compared to the more urbanized states such as Illinois and Michigan.

    The default Topographic basemap is better suited for a reference map (which emphasizes the geographic location of features) than a thematic map (which focuses on a specific theme, such as homelessness). Next, you'll change the basemap to something simpler.

  13. On the ribbon at the upper left of the screen, click Basemap and choose Light Gray Canvas.

    Basemaps

    The basemap changes.

    Count map with basemap

    The map gives a generalized visual representation of the data but not exact numbers. You can make the exact counts accessible through pop-ups, so that when the user clicks on a state, they'll see how many homeless people live there.

Configure pop-ups for the homeless population map

When you were exploring your data in ArcGIS Desktop, you used the Identify tool to show a feature's attribute information. In ArcGIS Online, you can access a feature's attribute information in a pop-up by clicking it. What's more, you can configure the pop-up to only show the information relevant to the map.

  1. Under the Homeless Counts layer, click the Show Table button to open the attribute table.

    Default table

    The attributes and their aliases were published along with your layer.

  2. Close the attribute table. On the map, click North Dakota.

    Default pop-up

    The default pop-up opens. It displays all of the visible data in the attribute table. The pop-up could be better, however. First, this map is only about homeless counts, but other attributes are also visible. Second, the state name is displayed twice. Third, the attribute values for population and count include decimals.

  3. Close the pop-up. In the More Options menu of the Homeless Counts layer, click Configure Pop-up.
  4. In the Pop-up Properties pane, clear the text in the Pop-up Title box. Click the Add Field Name button next to the text box and choose State {STATE_NAME}.

    Pop-up Title

    A field name in curly brackets is substituted with the attribute for that field when a feature is clicked. For instance, when you click North Dakota, the pop-up will display North Dakota as the title.

  5. Under Pop-up Contents, for Display, choose A list of field attributes.
  6. Click Configure Attributes.

    Configure Attributes

  7. In the Configure Attributes window, uncheck the boxes next to all fields except Homeless Count (2013).

    Pop-up attributes

    Now, only Homeless Count (2013) will be displayed in the pop-up.

  8. Click the blank space anywhere on the Homeless Count (2013) row. In the attribute options on the right side of the window, change Format to 0 decimal places.

    Format box

  9. Click OK. In the Configure Pop-up pane, click OK.
  10. On the map, click North Dakota (or any state) to view the pop-up.

    Count pop-up

    Your pop-up shows only the information that this map is supposed to show.

  11. Close the pop-up. On the ribbon, click Save and choose Save As.

    Save button

  12. In the Save Map window, type the following information:
    • Title: Number of Homeless, 2013
    • Tags: homelessness, homeless counts, United States, 2013 (you can add additional tags)
    • Summary: Map of homeless counts by state in the United States

    Tip:

    When entering tags, press Enter after each tag to enter it as an individual tag. Alternatively, type all of the tags separated by commas and press Enter.

    Save Count map

  13. Click Save Map.
  14. On the ribbon, click Share.
  15. In the Share window, check the appropriate boxes to share your work either with Everyone or with your organization. Click Done.

Symbolize the layer by homeless percentage

Although the total number of homeless people in North Dakota is fairly small, that doesn't mean the problem is less severe for its scale. A state with 38 million people, such as California, is going to have more homeless people than a state with 800,000 people, such as North Dakota. But the state with more people will also have more resources to handle the problem. To make your audience see past mere homeless counts, your next map will normalize counts by population to show what percentage of a state's population is homeless.

Since your second map will be similar to your first, you'll start by making a copy of your first map.

  1. In the Number of Homeless, 2013 map, click Save and choose Save As.
  2. In the Save Map window, edit the following fields:
    • Title: Homeless as Percentage of Population, 2013.
    • Tags: Replace the homeless counts tag with homeless percentages.
    • Summary: Replace homeless counts with homeless percentages.

    Save percent map

  3. Click Save Map.

    The map title changes. You can now make and save edits to the map without affecting your first map. As with your previous map, you'll change this map's symbology and configure its pop-ups to show the relevant data.

  4. Rename the Homeless Counts layer Homeless Percentages.
  5. Under the Homeless Percentages layer, click the Change Style button.

    In your previous map, you used graduated symbols to represent the count of homeless people. One reason you didn't use color shading was that you didn't want to suggest that homeless people were evenly distributed throughout each state. Now that you're dealing with a ratio, that consideration doesn't apply.

  6. Under Choose an attribute to show, confirm that Homeless Count (2013) is selected.
  7. Under Select a drawing style, under Counts and Amounts (Color), click Select. Click Options.

    Change Style - Homeless Percent

  8. For Divided by, choose Population (2013).

    Divided by Population

    The symbols and legend update.

    Change Style legend - Homeless Percent

    The values represent homeless counts divided by population. More practically, the values represent the number of homeless people per person in a population. The values currently don't make much sense—you can't have .0009 of a person. To fix this, you can express the values in a different form, multiplying them by 10,000 to show the number of homeless people per 10,000 people. That way, your values will be whole numbers, not fractions.

    To multiply these values by 10,000, you'll add a new field to the attribute table and do a little arithmetic.

  9. At the bottom of the Change Style pane, click Cancel. Click Cancel again to return to the Contents pane.
  10. In the Contents pane, under the Homeless Percentages layer, click the Show Table button.

    Configured table

    In addition to the information already stored in the attribute table, you'll create a field to show the number of homeless people per 10,000.

  11. Click the Options button and choose Add Field.

    Options

  12. In the Add Field window, fill in the following information:
    • Name: HomelessPer10000
    • Alias: Homeless per 10,000
    • Type: Integer

    Add Field

  13. Click Add New Field.
  14. On the right side of the attribute table, click Options and choose Show/Hide Columns. Ensure that Homeless per 10,000 is checked.

    The new field is now visible in the table, but it's currently empty. You'll have to calculate its values.

  15. Click the header of the Homeless per 10,000 column and choose Calculate.

    Calculate

  16. For Language, choose SQL.
  17. In the Expression Builder, under HomelessPer10000 =, click the appropriate fields and mathematical signs to create the expression ( Homeless13 / Pop13 ) * 10000.

    Table expression

    The expression divides the homeless count of each state by the state's population and multiplies the result by 10,000.

  18. Click Calculate. Confirm that the values were added to the Homeless per 10,000 field and close the table.

    Now you can symbolize the map and configure pop-ups using this layer.

  19. In the Contents pane, for the Homeless Percentages layer, click the Change Style button.
  20. For Choose an attribute to show, choose Homeless per 10,000. Under Select a drawing style, select Counts and Amounts (Color) and click Options.

    Change Style - Homeless Percent

  21. In the symbology options, click Symbols.

    Symbols

    Since you're symbolizing by color instead of size, the symbols window has several color ranges for you to choose from.

  22. Click the color range that goes from red to yellow and click OK.

    Yellow to red range

    The map updates with the new colors.

  23. As you did in the previous map, check Classify Data and change the number of classes to 5.

    Default percent map

    This map doesn't seem to show the problem in North Dakota either. North Dakota is in a middling class while a small number of outliers take up the higher classes. However, unlike the previous map, the problem isn't that North Dakota has a low value; in fact, it has one of the highest values in the country. The problem is that the class breaks between categories are skewed by three or four exceptionally high values.

    The Natural Breaks classification method is useful for showing outliers, but your goal is to show that North Dakota is in the top percentage of states.

  24. Under Classify Data, change Using to Quantile.

    Quantile

    Quantile determines class breaks by distributing an equal number of values into each class. Since your data has 51 features (all states plus the District of Columbia) and you are using five classes, each class has roughly 10 features.

    Percent map

    North Dakota is in the highest class, which constitutes the top 10 states in terms of its homelessness rate.

  25. At the bottom of the Change Style pane, click OK and click Done.

Configure pop-ups for the homeless percentage map

Next, you'll configure pop-ups for the map. Since the Homeless per 10,000 attribute doesn't have a self-explanatory title, you'll configure a custom attribute display that better explains the data.

  1. In the Contents pane, in the More Options menu of the Homeless Percentages layer, click Configure Pop-up.
  2. Under Pop-up Contents, change Display to A custom attribute display.

    Custom attribute display

  3. Click Configure. In the Custom Attribute Display window type, or copy and paste: In 2013, {STATE_NAME} had {HomelessPer10000} homeless people for every 10,000 people.

    Custom Attribute Display window

  4. Use the Bold button to bold {HomelessPer10000}.
  5. Click OK. In the Configure Pop-up pane, click OK.
  6. On the map, click North Dakota (or any state) to view the pop-up.

    Percent pop-up

  7. Close the pop-up.
  8. Save and share the map.

    With your second map, more of the story comes into focus. Although North Dakota has a low homeless count, that count is relatively high for its population. However, there are still states that have both higher counts and higher percentages, such as California and New York. To finish the picture of homelessness in North Dakota, you'll create one more map: change.

Symbolize the layer by homeless change

Change plays an important role in determining the severity of homelessness in a state. A state with low or negative change, even if it has high homeless counts and percentages, will likely have enough shelters and resources from previous years to deal with the problem. A state with high change, however, may not have such infrastructure, exacerbating homeless conditions. Your last map will depict change in homeless counts from 2012 to 2013.

  1. In your Homeless as Percentage of Population, 2013 map, click Save and choose Save As.
  2. In the Save Map window, edit the following fields. When you finish, click Save Map.
    • Title: Percent Change in Homeless Counts, 2012-13.
    • Tags: Replace the homeless percentages tag with homeless change.
    • Summary: Replace homeless percentages with homeless change.

    Save Change map

  3. In the Contents pane, rename the Homeless Percentages layer Homeless Change.

    You may remember that after you joined the Homeless Data Excel sheet to the United States layer in ArcMap, the Change field data was reformatted with fractions instead of percentages. You'll multiply those fractions by 100 to convert them to percentages.

  4. Under the Homeless Change layer, click the Show Table button.
  5. If necessary, on the right side of the table, click the plus sign and check Homeless Change (2012-13).

    Show columns

  6. Click the header of the Homeless Change (2012-13) column and choose Calculate.
  7. For Language, choose SQL.
  8. In the Expression Builder, create the expression Change * 100.

    Table expression

  9. Click Calculate. Confirm that the values were added to the Change field and close the table.
  10. In the Contents pane, under the Homeless Change layer, click the Change Style button.

    Some states have had declines in homeless count, while others have had increases. To show this difference, you'll use a diverging color scheme.

  11. In the Change Style pane, under Choose an attribute to show, choose Homeless Change (2012-13). Under Counts and Amounts (Color), click Options.

    Change Style - Homeless Change

    For the classification scheme, you'll use Natural Breaks instead of Quantile to emphasize the fact that North Dakota had an exceptionally high change. You'll also increase the number of classes to show that despite the large variation between states, North Dakota still stands out.

  12. Check Classify Data. Change the number of classes to 7.

    Change Style classes

  13. Click Symbols. In the list of color ranges, in the second row from the bottom, choose the diverging green and purple color scheme.

    Diverging colors

  14. Click OK. At the bottom of the Change Style pane, click OK and click Done.

    Change map

    In this map, green states experienced increased homeless counts, while purple states experienced decreased homeless counts. The white states had relatively little change either way. North Dakota is the only state in the highest class. This will be your most persuasive map for informing your audience of the homeless problem in North Dakota.

Configure pop-ups for the homeless change map

You'll now configure a pop-up to display the values.

  1. In the More Options menu of the Homeless Change layer, click Configure Pop-up.
  2. In the Pop-up Properties pane, under Pop-up Contents, click Configure to open the Custom Attribute Display window.
  3. Clear the existing text. Type, or copy and paste: Between 2012 and 2013, {STATE_NAME} experienced a {Change} percent change in homeless counts.

    Custom Attribute Display window

  4. Use the Bold button to bold {Change}.
  5. Click OK. In the Configure Pop-up pane, click OK.
  6. On the map, click North Dakota (or any state) to view the pop-up.

    Change pop-up

  7. Close the pop-up.
  8. Save and share the map.

In this lesson, you used your layer to create three maps of the United States, each focusing on a different aspect of homelessness. In the next lesson, you'll share your results by creating a web app to allow your audience to compare all three maps side by side.