How GIS Helped Riverside County Navigate the Complex Redistricting Process

Geographically and by population size, Riverside County in California boasts a challenging environment for its redistricting process. With a population of over 2.4 million people, it's the fourth most populous county in California and the tenth most populous county in the US. The largest city in the county has 335,000 residents, and the smallest has just over 10,000 residents. In addition to the variance in population size, the county has a variety of communities that span across mountainous regions as well as through desert areas. The diversity in population, coupled with landscape of the county, makes it challenging to connect with everyone during the redistricting process.

Prior to the redistricting process, the US Census Bureau conducts a count of the US population every 10 years. The goal is to count everyone once—and only once—and in the geographically correct location. Geography provides the critical framework for the Census Bureau to complete its work, and geographic information system (GIS) technology provides insight and a deeper understanding of the data. The data can then be presented in a visually appealing way using maps and dashboards to tell a story.

Redistricting is the process by which local and state governments use decennial census data to redraw boundaries of election districts to have an equally represented population distribution within each district. The election boundaries are delineated based on the distribution of population across a defined census boundary. In a large county like Riverside, leaders must ask, How do you begin doing redistricting, and in particular, how do you begin to recognize all the communities of interest (COI)—knowing that communities of interest is a term that means a lot of different things?" said Tom Mullen, director of broadband services for Riverside County.

Every state and local government must consider their communities of interest when beginning their redistricting process. In California, a COI is a group of people with shared concerns, interests, and characteristics. Every COI is unique; for example, one might be formed around neighborhoods, a physical landscape, cultures, values, or other demographic variables. "[COI] could mean minority-speaking populations in a geography. It could mean a group of teachers," added Mullen.

During the 2021 redistricting effort, Riverside County's board of supervisors had to determine how to balance the political representation across five supervisorial districts. The county had to take into consideration multiple COIs, federal and state constitutional requirements, and federal and state statutes.

One consideration for Riverside County was the incarceration population count.

In most states, incarcerated people cannot vote but are counted during the creation of the supervisorial districts. Meaning, they are counted where they are incarcerated, not where they last lived prior to their imprisonment. This can cause an inaccurate imbalance of the incarceration population distribution during the redistricting process.

In 2021, California passed legislation to adjust its census data to associate incarcerated people with their last known address rather than where they are imprisoned.

This new legislation impacted how quickly Mullen and staff could produce proposed maps with demographic analysis for their redistricting commission and board of supervisors. In the previous redistricting cycle, Mullen noted that this was a cumbersome process that led to longer turnaround times to the officials.

According to Mullen, the Esri Redistricting software as a service simplified the drawing of the maps and the balancing of the demographics immensely. Esri's suite of products enabled Mullen's team to publish maps while reflecting the changes back to the community to solicit feedback. The board of supervisors wanted to demonstrate transparency in the redistricting process and highlight the value of community input during the once-a-decade initiative. Mullen and his staff produced over 100 maps before getting to the final versions of the supervisorial districts. 

When collecting and sharing data, timeliness is important because there are many stakeholders who interact with the data that Mullen's team provides. With the latest census data, officials at Riverside County needed to measure their data against the criteria established at the state and federal levels.

"We began in August and had to produce a final map in December. We had a very short amount of time to go through the public hearing and notice processes that must happen each time you need to notify the public that a new map has been published," Mullen said.

To do this, the county implemented Esri Redistricting, a web-based software as a service that helps users create redistricting plans that adhere to constitutional and legislative criteria. It helps states and local governments maintain electoral district boundaries that reflect the latest population changes. Mullen's staff leveraged additional GIS technology such as ArcGIS Survey123, ArcGIS Dashboards, and ArcGIS StoryMaps. These were used in combination with Esri Redistricting to ensure simple and intuitive data gathering from community interest groups, community members, and other individuals.

The process of creating these district maps is iterative in nature and typically consists of community members, legislators, and county staff, all generating proposed mapping plans for the county. Once the proposed maps have been prepared, the redistricting commission and board of supervisors review changes in real time, with the option to move boundary lines during collaborative feedback sessions. The final maps were approved by the board of supervisors during a public hearing on December 7, 2021.

After the redistricting process has been completed, Mullen's team shared the results with Riverside County residents using Esri's ArcGIS StoryMaps. "This data lives on our website for 8 to 10 years. It's critical that we have the flexibility and accuracy of the maps, data analysis, and demographic charts to share in a meaningful way with internal and external audiences," said Mullen.

By implementing Esri Redistricting, Riverside County staff successfully produced maps that worked well for stakeholders while meeting state and federal guidelines, all while under a tight deadline.

How will things change over the next decade? From experience, Mullen believes that the Esri Redistricting solution, together with other Esri ArcGIS products, will again assist the county in keeping the public informed during the redistricting process. "Had we not had a tool of the caliber that we did, we would not have been able to turn those maps around, and we would not have the positive feedback from the public, elected officials, committee members, and our IT professionals," said Mullen.