Explore a map of election results

Mapping election results is one way to share information about elections so that everyone can see them. In this tutorial, you'll recreate a web map that visualizes United States voting patterns using county-level election results. You'll add layers, adjust their styles, configure pop-ups, and format labels to produce a clean, interpretable map.

As you work through the tutorial, use the data to consider these questions:

• Which candidate won? Where did they win?
• Which states are considered as reliably voting for one party or another, and what do their electoral maps look like?
• What was the winning candidate's margin of victory? What might this mean for the idea of elections as a mandate, or the authority for the winning candidate to govern?
• Where did people not vote? What factors may have contributed to this pattern? Consider both choice and systemic constraints.

This tutorial was last tested on April 27, 2026.

View final result

Requirements

• You can complete this tutorial without an ArcGIS account. However, to complete the steps to save the map, you must have a free ArcGIS public account or a User or higher member role in an ArcGIS organization (see options for software access)

Explore a map of election results

Open a map

If you've encountered a presidential election result map in the news, on social media, or elsewhere, chances are it showed the winning candidate by state. This is one way to map results, but it tends to hide a lot of the nuance present in elections. For example, looking at a map that shows the winning candidate by state might make it look like each state is weighted equally in determining the president. This isn't the case, however: each state contributes a number of electoral votes to the candidate that wins the popular vote in that state. Electoral votes are allocated based on the population of the state, so states with smaller populations, such as North Dakota, have fewer electoral votes than states with bigger populations, such as Texas.

You'll open a map showing election results for the 2012 presidential election and prepare the data for visualization.

1. Open the Visualize Election Results 2012 web map.

   

   This map contains several layers that will be used in the tutorial. The 2012 Presidential Election by State layer is currently shown on the map. From the map's legend, you can tell that states where the Democratic candidate won the popular vote are shown in blue, and states where the Republican candidate won the popular vote are shown in red.

   This type of map is called a choropleth. It is a way of presenting quantitative data. In this case, the choropleth identifies where one party or the other won the most number of votes, using filled areas of color, or states.

   This choropleth map is misleading, however. The human brain automatically equates size with importance.

   

   For example, the example image shows the states of New Mexico and Massachusetts at the same map scale. Subconsciously, you might interpret the state with the largest land area, New Mexico, as the most important because it appears bigger, and the smaller state, Massachusetts, might seem less important. But land doesn't vote, people do. Massachusetts has 4.5 million more residents than New Mexico, but when the two states are shown with the exact styling on a map, that's hard to tell.

2. On the map, click your state.

   

   Note:

   The example images throughout this tutorial show the state of Pennsylvania. If you don't live in the United States, you can explore data for Pennsylvania when instructions prompt you to choose your state.

   An informational pop-up appears. The pop-up lists the party of the state's winning candidate, as well as how many electoral votes that state has.

   For your state, answer the following questions:

   • How many people did your state have in 2010?
   • How many electoral votes did it have?

   The United States president isn't elected by the popular vote, or the total number of votes. Instead, in most states, the candidate with the most votes in each state receives all that state's electoral votes, and the candidate with the most electoral votes wins the national election. Electoral votes are allocated based on the population of the state. Wyoming has 3 electoral votes for its approximately 560,000 people. California has 55 electoral votes for its nearly 28 million people.

3. On the map, click another state.

   If your state has a large land area, choose a small state such as Delaware. If your state has a small land area, choose a large state such as Nevada.

   Answer the following questions:

   • What is the population of this state?
   • How many electoral votes does it have?
   • How does this compare to your state?

   Next, you'll choose whether you want to save a copy of the map. If you just want to explore this data, you can complete the tutorial without signing in to ArcGIS. If you want to save your work, you need to sign in to your account now before making any changes to the map. Signing in once you've begun changing the map will revert it back to its original state and you'll lose any changes you made.

4. If you want to save a copy of the map, click Sign In. Sign in using your ArcGIS account.

   Note:

   If you don't have an ArcGIS organizational account, you can sign up for a free public account.

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

   

6. In the Save map window, enter the following information:
   • For Title, type Election results visualization tutorial.
   • For Summary, type This map contains state and county-level election data for the 2012 presidential election. It was built for instructional purposes for the tutorial Explore a map of election results.

   

   Tip:

   Adding your name or initials to the map title isn't necessary, but helps distinguish this map from similar content that may exist in your organization or ArcGIS Online.

7. Click Save.

Interpret statewide election results

If choropleth maps aren't the best way to show statewide election data, then what is? You'll explore other ways of visualizing statewide data, such as with graduated symbols. Graduated symbols are shapes that appear larger or smaller depending on the quantity or value being mapped.

1. On the Contents toolbar, click the Layers button.

   

   The Layers pane shows the layers contained in the map.

2. If necessary, click the 2012 Presidential Election by State layer to select it.

   When a layer is selected, a blue bar appears next to it.

   

   Selecting a layer allows you to use tools on the Settings toolbar to work with it. For example, you can edit the layer's style and pop-ups. You'll start by changing the map to show the state's winning candidate by electoral votes.

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

   

   The map is currently styled to show the party of the winning candidate.

4. For Choose attribute, click Field.

   

5. In the Select fields window, search for and check the box for Electoral College 2012. Click Add.

   

   The map updates to show each state's election results using different sized circles, or graduated symbols.

   

   The color of the circle still corresponds to the party of the winning candidate, and the size of the circle represents how many electoral votes the candidate won per state.

6. In the Styles pane, click Done.

   Because most states have a winner-takes-all approach to votes, whichever candidate wins the most votes gets all that state's electoral votes. So, while this map does a better job of showing how many people voted in each state and how consequential it was, this system hides information about the popular vote. Said another way, this map hides the candidate's margin of victory, or how many votes they won by.

   Note:

   Nebraska and Maine split their electoral votes. In the 2012 election, all electoral votes went to a single candidate.

   You'll create a chart in the layer's pop-up to explore the number of votes each candidate received.

7. On the Settings toolbar, click Pop-ups.

   

   The pop-up currently has several kinds of elements, including a title, a Text element, and a Fields list element showing some facts about the state.

8. In the Pop-ups pane, click Add content and choose Chart.

   

   The Configure chart window appears. You can choose the kind of chart you want to add and the fields you want to populate it with.

9. Click Select fields.

   

10. Check the Democratic, Republican, and Other check boxes. Click Done.

    

    A bar chart appears in the sample pop-up. Because the chart is currently displayed with default colors, they don't match the colors you set on the map.

11. In the Configure chart window, click the color swatch for the Republican candidate.

    

12. In the Select color window, use the color slider to choose a shade of red. Click Done.

    The example pop-up updates to show the new colors.

13. If necessary, change the color for the Democratic candidate to a shade of blue.
14. Point to each bar in the pop-up to show a label with the number of votes each candidate received.

    

15. On the map, click your state. Answer the following questions:
    • What does the chart tell you about the winning candidate's margin of victory in 2012?
    • What state has the largest margin of victory? The smallest?

Map election results by county

A more granular way of looking at election data is at the county level. During elections, votes are counted at the county level and then aggregated up to the state. Looking at county-level results can help you better visualize the margin of victory.

1. In the Contents pane, for the 2012 Presidential Election by State layer, click the Hide button. For the 2012 Presidential Election by County layer, click the Show button.

   

   Election results now are shown by county. This layer is currently shown in the same choropleth style that was used for the state layer. While breaking the election results data down by county makes it easier to see patterns in how people are voting, it still hides important information about how many people are voting.

2. In the Contents pane, ensure that the 2012 Presidential Election by County layer is selected. On the Settings toolbar, click Styles.

   This layer is currently shown using the Predominant category style. This style evaluates the numeric value of two or more categories and shows a color based on the higher value.

3. For Predominant category, click Style options.

   

4. Expand Transparency by predominant percentage. Turn on Set transparency based on the predominant percentage.

   

   The map still shows the color of each county based on the winning candidate, but now has a transparency applied. The lighter each county is, the lower the margin of victory in that county. For example, in most counties in Utah, the dark red tells you that the Republican candidate won by a lot of votes. In south Texas, the dark blue tells you that the Democratic candidate won by a lot of votes.

   

   As you click these counties, you may also notice that the population of each varies. For example, in Duchesne County in Utah, a total of 6,379 votes were cast, 5,698 for the Republican candidate. In Cameron County, Texas, 76,895 votes were cast, 49,975 for the Democratic candidate.

   Next, you'll try a map style that shows county votes relative to their population.

5. In the Styles pane, click the Back button. Click Predominant category and Size.

   

   Now each county is shown by the winning candidate's party and the population. The larger circles show counties with higher numbers of voters. Smaller circles show counties with lower numbers of voters. On this map, the counties that include big cities, such as Los Angeles and Chicago, stand out because of their large, concentrated population.

   

   So far, you've been focusing on the voting population. Another metric to consider is voter participation, or how many eligible voters are casting a vote.

6. In the Contents pane, hide 2012 Presidential Election by County and show 2012 Presidential Election by County with Non-Participants.
7. On the map, click a county shown in yellow.

   

   This map shows what the hypothetical results of the 2012 election would be if people who didn't vote were considered to have cast their vote for an imaginary non-candidate. In counties shown in yellow, more people didn't vote than did vote, so in these places, the map shows the non-candidate as the winner.

8. On the map, click your county. Answer the following questions:
   • Which candidate won your county?
   • Do you see any regional patterns on this map?

   There are many reasons people can't or choose not to vote. This map uses the total adult population (people over the age of 18) to show nonparticipation. This is a proxy for the voting population that doesn't consider factors such as access to polling locations, voting eligibility, and voter registration.

9. In the Layers pane, hide 2012 Presidential Election by County with Non-Participants and show Election 2012 Voter Turnout by State.
10. On the Contents toolbar, click Legend.

    

    This layer shows the approximate percent of citizens who voted in each state. These are estimated numbers provided by the United States Census, not actual counts. States shown in darker shades of orange had higher percentages of people who voted in this election. States shown in darker shades of gray had lower percentages of people who voted in this election.

    Which states had higher percentages of voting participation? Within these states, do you notice any patterns in the percentage of people who were registered to vote who then cast a vote compared to the percentage of the total population who chose to vote?

11. Click different states on the map to explore the data.

There is no one right way to map election data, but there are several considerations to keep in mind when you choose how you want to visualize the results. That's why tools such as interactive web maps are useful for visualizing the data in different ways. Each map style you used today showed a different aspect of the same election data and answered a different question or showed a different pattern in the data. Using different visualization techniques such as these can help increase transparency in election mapping.

You can find more tutorials in the tutorial gallery.

Acknowledgements

• Election data adapted from MIT Election Data and Science Lab, 2018, "County Presidential Election Returns 2000-2024", https://doi.org/10.7910/DVN/VOQCHQ, Harvard Dataverse, V20, UNF:6:xvsJJxrfXMIvzAuDYlfvVw
• Election 2012 Voter Turnout by State table 4B: United States Census Bureau
• Human Geography Map sources: Esri, TomTom, Garmin, FAO, NOAA, USGS, OpenStreetMap contributors, and the GIS User Community