Create a policy map

A policy map is a map that shows areas where policy intervention should be prioritized. It is important to make the map clearly and readily understandable for elected officials who may not have expertise in a specific area you are advocating for. The map should also be compelling and motivate action. You'll create a policy map that shows low birth weight by county across the United States. Then, you'll focus on the state of Mississippi. This map will emphasize the counties in most need for intervention programs to improve newborn health outcomes.

Your map will show counties close to reaching the CDC goal for low birth weight and counties that are the biggest outliers, where intervention may have the most impact.

Add data to a new map

First, you need data. ArcGIS Living Atlas of the World has lots of authoritative GIS data, so you'll search it for county data on birth weight.

  1. Sign in to your ArcGIS organizational account.
    Note:

    If you don't have an organizational account, see options for software access.

  2. At the top of your organization home page, click Content.

    Content tab

  3. On the ribbon, click Living Atlas.

    Living Atlas tab

    This tab contains available content from ArcGIS Living Atlas.

  4. In the Search Living Atlas box, type County Health Data. In the search results, click County Health Rankings 2023.

    Living Atlas search and result

    The feature layer's item page appears.

    This page contains documentation about the data and its source. The data comes from County Health Rankings & Roadmaps, so it should be trustworthy and reliable. But does the layer have data on birth weight?

  5. Click the Data tab.

    The data attributes are displayed as a table. The table contains a lot of data, so you'll search a list of attribute field names for what you want.

  6. In the top corner, click Fields.

    Fields button

  7. In the search bar, type Birth.

    The search returns several results, many about low birth weight percentage. You'll be able to make your policy map with this layer.

  8. Click the Overview tab.

    One of the links in the description leads to a list of downloadable Excel spreadsheets. The 2023 County Health Rankings National Data spreadsheet is the one the layer is based on. If you download it and open the Ranked Measure Sources & Years tab, you'll learn that the low birth weight data is for 2014 to 2020.

    It's important to understand your data and where it comes from before you use it in a policy map. Always read the details page or metadata. Now, you're ready to add the data to a new map.

  9. On the item page, click Open in Map Viewer.

    Open in Map Viewer button

    The map opens and shows the county boundaries of the United States.

    Default map

  10. On the Contents (dark) toolbar, click Save and open and click Save as.

    Save as option

    Note:

    The toolbars in Map Viewer can collapse to allow more room to view the map. If the labels on the Contents toolbar are not visible, click Expand at the bottom.

  11. In the Save map window, enter the following parameters:
    • For Title, type Low Birth Weight by County, 2014-2020.
    • For Tags, type Birth Weight, Newborns, United States, and public health.
    • For Summary, type This map shows the rate of low birth weight by county relative to the 2020 CDC goal of reducing the rate of infants born with low birth weight to 7.8 percent.
  12. Click Save.

Discover nationwide patterns

Before you focus on your state of interest, you'll learn about some of the patterns nationwide to better understand the birth weight situation. When looking for patterns in your data, it's helpful to try styling the data in different ways.

First, you'll change the basemap. A common default is the Topographic basemap, which is designed as a reference map. To emphasize your data, you'll use the Human Geography Map basemap, which has fewer topographic features.

  1. On the Contents toolbar, click Basemap. In the Basemap pane, scroll down and click Human Geography Map.

    Basemap pane showing the Human Geography Map basemap

    The basemap changes. Next, you'll change the style of your data so that counties with higher and lower percentages of low birth weights have different colors.

  2. On the Contents toolbar, click Layers. In the Layers pane, expand County Health Rankings 2023 and select the County layer.
    Note:

    You may need to zoom in for the layer to be visible at the county level.

    County Health Rankings 2023 expanded in the Layers pane with the County layer selected

  3. On the Settings (light) toolbar, click Styles.

    Styles button

  4. In the Styles pane, for Choose attributes, click the remove button for the Percentage of adults that report fair or poor health attribute.

    Remove button in the Styles pane

  5. Click Field.

    Field button

  6. In the Select fields window, search for birthweight. Select Percentage of births with low birthweight.

    Percentage of births with low birthweight field

  7. Click Add.

    Because this field is a percent or rate, the color drawing style (instead of size or single symbol) is chosen by default and the counties are automatically styled with a high-to-low color ramp.

    Map styled by color

    The legend explains the distribution of the colors. In the darkest counties, more than 10 percent of infants born were considered low birth weight. In the lightest counties, less than 6 percent of infants were born with low birth weight. Many counties in the southeastern part of the country have high percentages of low birth weights, as do several counties in New Mexico and Colorado.

    Next, you'll review a histogram to better understand the distribution of values.

  8. For Pick a style, in the Counts and Amounts (color) box, click Style options.

    Style options button

    The Style options pane appears, showing the histogram.

    Histogram of default distribution of values

    The minimum value is 0.0 (suggesting some counties have no data) and the maximum is 21.7. The x̅ symbol indicates the average value, which is 7.9 percent. This average shouldn't be considered a national average, however. The average of your data treats all counties as equal, meaning it does not account for population differences between counties.

    The values of 10.4 and 5.5 on the side of the histogram represent one standard deviation away from the average. These values were assigned as the cutoffs for the darkest and lightest colors. While the default statistical classification of the data is okay, you can change the settings to uncover more patterns.

  9. For Theme, choose Above and below.

    Theme changed to Above and below

    The style of the map changes. Now, two distinct colors are used to depict values above and below the average. The cutoffs for the darkest and lightest colors remain the same. However, a new handle has been added to the histogram with the value 7.93, an approximation of the average.

    According to statistics published by the CDC, the national rate of low birth weights in 2020 was 8.24 percent. You'll change the middle handle to match this value.

  10. On the histogram, click the middle handle value, type 8.24, and press Enter.
    Tip:

    You can also adjust a handle by dragging the handle.

    Adjusted histogram

    The colors of the counties adjust on the map.

  11. Change the lower handle to 7.8.

    This percentage was the CDC's 2020 goal for average low birth weight. By styling the map with this value as the average, you'll have a clearer idea of which counties will need help to achieve the goal.

    The dataset has a long tail. This means that there is a large outlier (the maximum value of about 22 percent). Outliers aren't styled any differently than counties that are only one standard deviation from the average. You'll change the data distribution to better view the counties that need the most help.

  12. Change the top handle to 11.

    Now, your map has more gradation between values above the CDC goal.

    Next, you'll change the color ramp. Your basemap is light, so you want a color ramp with a light center to draw attention to the darker extremes. Additionally, you want to de-emphasize values below the CDC goal, because they aren't as relevant to your policy map.

  13. Under Symbol style, click the color ramp.

    Symbol style color ramp

  14. In the Symbol style pane, for Colors, click the color ramp.
  15. Choose the Orange and Gray 1 color ramp.

    Orange and Gray 1 color ramp

  16. Click Done.
  17. In the Style options pane, click Done. In the Styles pane, click Done.

    Map styled to emphasize high values

    Now, the map visually indicates which counties are of highest concern, exceeding the 2020 goal of 7.8 percent of infants born with low birth weight.

  18. On the Contents toolbar, click Save and open and click Save.

    The map is saved.

Configure pop-ups

When you click the data on your map, a pop-up appears with information about that data's attributes. It would be useful for your users if they could click a county and see the percentage of births in the county with low birth weight.

  1. Click any county on the map to open its pop-up.

    Default pop-up

    The default pop-up contains a description of the percent of adults reporting poor or fair health and the county's ranking in health outcomes and health factors. Since your map is about the rate of low birth weight infants, you'll configure the pop-up to show only the information relevant to your policy map.

  2. Close the pop-up.
  3. On the Settings toolbar, click Pop-ups.

    Pop-ups button

    The Pop-ups pane for the County layer appears.

  4. In the Pop-ups pane, click the Options button for Text and click Delete.

    Delete option

  5. Click Add content and choose Text.
  6. In the text editor that appears, type (or copy and paste) the following text:

    The percent of babies born at low birth weight (5.5 lbs or less) between 2014 and 2020 in {COUNTY}, {state}, was {v037_rawvalue} percent.

    In 2020, the national rate of low birth weight infants was 8.24 percent. The CDC set a goal in 2007 to reduce the rate of low birth weight infants to 7.8 percent by 2020.

    The text {v037_rawvalue} is the field name for the Percentage of births with low birthweight attribute. You'll format the pop-up text so key information is more visible.

  7. Highlight {v037_rawvalue} and click the Bold button.

    Bold button

  8. Highlight the text 8.24 percent and click the Bold button.
  9. Click OK.

    The pop-up preview updates with the new pop-up text.

    Configured pop-up

    The pop-ups now convey important information relevant to your policy map.

    Next, you'll add a chart to your pop-up to show differences in the rate of low birth weight by race and ethnicity.

  10. In the Pop-ups pane, click Add content and choose Chart.
  11. In the Configure chart window, click Select fields.

    Select fields option in the Configure chart window

  12. In the search bar, type birthweight. Select the following fields:
    • Percentage of births with low birthweight (<2500g) for non-Hispanic American Indian and Alaska Natives
    • Percentage of births with low birthweight (<2500g) for non-Hispanic Asians
    • Percentage of births with low birthweight (<2500g) for non-Hispanic Blacks
    • Percentage of births with low birthweight (<2500g) for Hispanics
    • Percentage of births with low birthweight (<2500g) for non-Hispanic Whites

    Selected fields for low birth weight by race and ethnicity

  13. Click Done. In the Configure chart window, click Done.
  14. In the Pop-ups pane, under Media, for Title, type Percentage of births with low birth weight by race and ethnicity. For Description, type Point to each bar to see more information.

    Chart title and description updated

    The pop-up preview shows the chart.

    Pop-up configured with text and chart

    The pop-ups now convey important information quickly to users. Some counties did not report race and ethnicity data, so the chart will be blank.

  15. Close the pop-up and Pop-ups pane. Save the map.

Map low birth weight by state

The national map you created is helpful context for the issue of low birth weight across the United States. However, at the state level, decision makers may have more opportunities to leverage policy decisions over the counties. Furthermore, you want to explicitly highlight counties within a state where targeted intervention should be implemented to help the state reach the CDC's goal.

To do so, you'll map low birth weight by state to identify a state heavily impacted by low birth weight.

  1. In the Layers pane, point to the County layer and click the Visibility button to turn it off.

    Visibility button for the County layer

  2. Zoom out so that the State layer is visible in the map.
  3. In the Layers pane, click the State layer to select it. On the Settings toolbar, click Styles.
  4. In the Styles pane, for Choose attributes, remove Percentage of adults that report fair or poor health. Click Field and add Percentage of births with low birthweight.
  5. For Counts and Amounts (color), click Style options.
  6. In the Style options pane, update the following:
    • For Theme, choose Above and below.
    • For Symbol style, choose Orange and Gray 1.
    • On the histogram, change the upper break value to 11.

    Style settings for the State layer

  7. Click Done in both style panes.

    From this view, you determine that the state with the highest rate of low birth weight infants is Mississippi. Other states with high rates include Louisiana and Alabama.

    Map showing the percentage of low birth weight by state

Identify counties for intervention

You'll save a copy of your map and filter your data to only show counties in Mississippi, the state you identified as having the highest rate. Then, you'll symbolize the Mississippi counties by how close or far the current low birth weight rate is from the 2020 goal.

Note:

If you want, you can perform this workflow on any state in the United States, not just Mississippi.

  1. On the Contents toolbar, click Save and open and choose Save as. Enter the following parameters:
    • For Title, type Priority Counties for Prenatal Programs.
    • For Tags, replace the United States tag with Mississippi.
    • For Summary, type Map showing Mississippi counties that should be prioritized for additional resources and programs in maternal and child healthcare to reduce the rate of infants born with low birth weight.
  2. Click Save.

    You are now working with a copy of your original map. Next, you'll filter the data.

  3. In the Layers pane, click the County layer. Click the Visibility button to turn it on again.
  4. On the map, zoom out until the counties appear.
  5. On the Settings toolbar, click Filter.

    A filter uses an expression to determine which features from a layer to show. You can create expressions using specific fields and attributes. Your data has a field for states, so you'll use that.

  6. In the Filter pane, click Add expression.
  7. For Expression, build the expression State Abbreviation is MS.

    Expression for filter

    The filter will only display features that fit these criteria.

  8. In the Filter pane, click Save.
  9. On the map, zoom in to Mississippi.

    Map centered on Mississippi

    Most of the counties in Mississippi are dark orange. The state has a higher range of low birth weight percentage by county. Next, you'll investigate the histogram of values for the state.

  10. On the Settings toolbar, click Styles.
  11. In the Styles pane, for Pick a style, in the Counts and Amounts (color) box, click Style options.

    In the Style options pane, you can view the histogram of low birth weight data for the state.

    Histogram for Mississippi counties

    The breakpoints you set at the national level remain, but the average has changed to 12.3 percent. While this average doesn't account for population differences between counties, the CDC does provide statistics by state for several health topics. In CDC reports, the Mississippi average low birth weight was about 12.3 percent.

    Decreasing low birth weight in counties already below the state average will likely require a lot of investment for not much payoff. It'll be more impactful for the state to focus on the counties with the highest percentages. Although these counties will require a lot of investment, the investment will make a bigger difference in the statewide average.

    It'll require fewer resources to help counties that are only slightly above the CDC goal of 7.8, so these counties should be highlighted for intervention, too. Your policy map will emphasize two groups of counties: those high above the CDC goal, and those just barely above it.

    To display these counties on your map in a way that makes clear which ones should be targeted for intervention, you'll use classified colors for counties with specific ranges of values instead of a continuous color ramp that gradually changes color as values increase or decrease. This style will make the map more readable at a glance and tell a simple, clear story to decision makers.

    Because the classifications you use will automatically focus only on counties above the CDC goal, you'll use a high-to-low theme.

  12. In the Style options pane, for Theme, choose High to low.
  13. For Symbol style, click the color ramp. For Colors, click the color ramp.
  14. In the Ramp pane, change Category to Reds and yellows. Choose Orange 4.

    Symbol style with Orange 4 color ramp selected

  15. Click Done and close the Symbol style pane. Under the histogram, turn on Classify data.

    Classify data setting turned on

    More options appear.

    By default, the method for classifying data is Natural breaks, which is a statistical method that automatically classifies the data into categories based on the data's distribution. You'll instead create manual breaks in the data: one for the national average (8.24), one for the statewide average (12.3), and one for values two times greater than the national average value (16.5).

  16. On the histogram, adjust the handles of the histogram (from bottom to top) to 8.24, 12.3, and 16.5.

    Manually configured histogram

    Next, you'll adjust the legend to make clear what each classification means.

  17. Scroll down to the list of classes. Click the > 16.5 - 20 label, add - Above 2x the national average, highest need for interventions, and press Enter.

    Added text to legend label

  18. Add to the remaining labels as follows:
    • For > 12.3 - 16.5, add - Above state average, very high need for interventions.
    • For > 8.24 - 12.3, add - Above national average, high need for interventions.
    • For 6.709 - 8.24, add - Below national average, moderate to low need for interventions.

    Labels for the policy map

  19. Click Done in both style panes.

    Priority map by counties

    This map indicates seven counties in greatest need of intervention, as well as clear categories of other counties where intervention may be advised.

  20. Save the map.

Add racial equity context

An important consideration in public health outreach is racial inequity and how it might inform intervention priority and methodologies. You'll duplicate the layer and change it to show the rate ratio of low birth weight infants born to Black and White mothers.

Note:

This tutorial will only investigate the disparity between Black and White mothers, but it is considered best practice to consider racial and ethnic disparities for all demographic groups within a specific population area. You're encouraged to try this workflow considering all available data for every racial and ethnic group.

  1. In the Layers pane, for the County layer, click the Options button and choose Rename.

    Rename option

  2. Add (Percent Low Birth Weight) to the end of the layer name and click OK.
  3. For the County (Percent Low Birth Weight) layer, click the Options button and choose Duplicate.

    A copy of the layer is created.

  4. Rename the County (Percent Low Birth Weight)-Copy layer to County (Ratio Black to White).

    Renamed layers

  5. If necessary, click County (Ratio Black to White) to select it. In the Styles pane, for Choose attributes, remove the Percentage of births with low birthweight field.
  6. Click Expression.

    Expression button

  7. In the expression builder window, replace New expression with Ratio of Percentage Black Low Birth Weight to Percentage White Low Birth Weight.
  8. In the expression box, build or copy and paste the following text:

    $feature["v037_race_black"]/$feature["v037_race_white"]

    Expression builder

    The field name for Percentage of births with low birthweight (<2500g) for non-Hispanic Blacks is v037_race_black and the field name for Percentage of births with low birthweight (<2500g) for non-Hispanic whites is v037_race_white. By building this expression, you are creating a ratio that compares the rate of low birth weight infants born to Black mothers compared to the rate of low birth weight infants born to White mothers. A value of 1 means the rate between the two groups is equal. A value above 1 indicates the rate of low birth weight infants born to Black mothers is higher than the rate for White mothers. A value below 1 indicates the low birth weight rate is higher for White mothers compared to Black mothers.

  9. Click Done.
  10. In the Styles pane, for Pick a style, click Color and Size. Click Style options.

    Style options for Color and Size

  11. In the Style options pane, for Theme, choose Above and below.

    The map updates to show chevron symbols that indicate whether the ratio is above or below the average ratio. You want to identify whether there is a higher low birth weight rate among Black mothers, so you will adjust the histogram accordingly.

  12. On the histogram, change the break points to 0, 1, and 2.

    Histogram adjusted for ratio values

  13. Below the histogram, for Size range, drag the right slider to 20.

    Size range slider

  14. For Symbol style, choose Red and Gray 1.
  15. Click Done in both style panes.

    Map showing both priority areas for low birth weight infants and racial inequality information

  16. On the Settings toolbar, click Pop-ups.
  17. Turn off Enable pop-ups.

    Now the only layer that will display pop-ups is County (Percent Low Birth Weight).

  18. Save the map.

You have created a policy map showing the racial disparity for low birth weight rate between Black and White mothers in addition to the counties with the highest low birth weight rates in Mississippi. The map reveals which counties in Mississippi are in most need of effective interventions to help the state move closer to the CDC's goal of 7.8 percent of infants born with low birth weight.

Share results with a web app

Previously, you created a policy map to show priority counties for increased prenatal programs in Mississippi. You want to present your policy map to key audiences within your state agency in a way that is clear and easy to understand. To do so, you'll create a web app.

A web app is a customized user interface that enhances your map's appearance, adds (or removes) functionality, and helps you integrate the map with other media. The decision makers who will see your map aren't GIS experts, so a web app that simplifies the user interface and calls attention to the most important details is ideal.

Choose an app template

First, you'll share your map and choose an ArcGIS Instant Apps template. You'll use the Sidebar app template.

  1. On the Contents toolbar, click Share map.

    Share map button

  2. In the Share window, choose Everyone (public). Click Save.
  3. On the Contents toolbar, click Create app and choose Instant Apps.

    Instant Apps option

    The Instant Apps gallery page appears in a new browser tab. It provides information and guidance to help you choose an appropriate app template.

  4. Locate the Sidebar template and click Choose.

    Sidebar template

  5. In the Create App window, click Create app.

    The app configuration window appears with an interactive preview of your app. The app is created based on the template you chose. Next, you will configure elements of the app to help users understand your map.

Configure the web app

When configuring an app, you can use the default express setup steps, which offer a subset of the configurable options. You can also accept all defaults or search for a setting that you want to change. If a setting isn't in the express setup, you'll be prompted to turn off express to access all configurable settings available for the app.

You'll change the color scheme to a lighter color to complement the map. You'll update the side panel to include detailed information about the map, along with the pop-up content and map legend to help users understand your map.

  1. In the configuration panel, click the step for Theme & Layout.

    Theme & Layout option

  2. For Select a mode, choose Light.

    Light option for Select a mode parameter

    The app preview updates to show the change and a draft is automatically saved.

  3. In the vertical toolbar, click Search settings and type details. In the list of suggestions that appear, click Edit details content.

    Search settings window with results for details

  4. Under Edit details content, click Edit.

    Edit button

  5. In the text editor, copy and paste the following:

    Low birth weight is a public health concern. Babies born at low birth weight are at higher risk of infection, developmental delays, and even death. The Centers for Disease Control and Prevention (CDC) has set a goal to reduce the national rate of babies born under 5.5 lbs to 7.8 percent. In 2020, the national rate of low birth weight infants was 8.24 percent, but the State of Mississippi was 12.3 percent.

    Another important consideration for the rate of low birth weight newborns is racial disparity. Several studies have determined that Black and African American women are consistently more likely to have an infant born with low birth weight compared to other racial and ethnic groups. In the state of Mississippi, the majority of counties reported higher rates of low birth weight infants born to Black mothers compared to the rate for White mothers.

    This map identifies four sets of counties in Mississippi:

  6. Press Enter to add a new line of text. Click the Bulleted List button and add the following bulleted list:
    • Counties above twice the national average, with the highest need for interventions.
    • Counties above the state average, with very high need for interventions.
    • Counties above the national average, with a high need for interventions.
    • Counties above the 2020 CDC Goal, with moderate need for interventions.
  7. Click Close.

    Your app is configured. You're ready to publish it.

  8. In the configuration panel, click Publish.

    Publish button

  9. In the Publish window, click Confirm.

    A success message appears when publishing is completed. The Share window appears, which includes a link to the app.

Review and share the app

Now that you have configured and published your app, you'll test it. Then, you'll update the sharing settings so you can share the app with stakeholders and decision makers.

  1. In the Share window, click Launch to open the app in a new browser tab.
  2. Click the Details tab to see the description you added.

    Details tab

  3. Click the Legend tab.

    Legend panel in the web app

    This panel displays your map's legend. It uses the labels you configured when you created the map. These labels are already descriptive, so they won't need to be changed.

  4. Click the Info tab and click any county on the map.

    Info tab displaying pop-up information

    The county's pop-up information is displayed in the side panel instead of as a pop-up.

  5. Close the app window.

    You have completed reviewing the app and are ready to share the app.

  6. In the Instant Apps configuration window, close the Share window and click Exit. In the confirmation window, click Exit.

    Your app's item page opens, where you can provide a summary, description, and terms of use, and credit the data source.

  7. Click Share.

    Share button

  8. In the Share window, select Everyone (public) and click Save.

    At the bottom of the item page, under URL, there is a link you can copy and share with stakeholders to view your app. (If you need to make changes, you can click the Configure button.)

In this tutorial, you found public data, styled it meaningfully, and configured informative pop-ups to create a policy map about low birth weight in Mississippi. You then created a web app that provided a detailed description and streamlined the user experience for decision makers.

This workflow can be replicated for many different geographies and with many types of health and demographic data, not just low birth weight. Which area of the United States or parts of the world are relevant to you? What kinds of challenges and issues can a policy map can help illustrate more clearly? Try exploring ArcGIS Living Atlas for a wide range of map topics and start mapping.

You can find more tutorials in the tutorial gallery.