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GIS Aids Maricopa County With Election Tasks

Geographically large and growing fast, Maricopa County, Arizona, had the greatest numerical population increase of any county in the United States between 2000 and 2001. With more than 3.2 million residents, it is the fourth most populous county in the nation and in areal extent, the 14th largest. Gilbert—the fastest growing city in the United States; Phoenix, the state's capital; and 23 other cities and towns are located in Maricopa County. The Maricopa County Recorder/Elections Department administers elections for the county's 1.5 million registered voters.

The department administers nearly continuous election cycles. City, school, and special district elections occur four times each year in March, May, September, and November. State and federal elections occur every two years in September and November, respectively. Throw in an occasional presidential preference election or countywide issue, and this makes for a busy schedule.

Department officials must ensure accurate boundaries, maintain the voter list, locate polling places, plan voting precincts, recruit and train poll workers, deliver supplies, and get the word out to voters for each and every election. Because elections in the county are sometimes decided by only a few votes, none of these tasks has a margin for error.

Fortunately, the department uses GIS for election tasks. Applications based on Esri GIS technology have helped radically transform internal business processes and data management in the department. Tasks that were previously cumbersome and labor intensive have been streamlined or eliminated with the implementation of an award winning, money saving GIS.

The Recorder/Elections Department GIS has worked its way into most aspects of the county's election processes. Some of the department's GIS activities include

  • Applications for precinct planning and redistricting
  • Maintenance of streets, districts, and jurisdictional boundaries in the GIS and voter registration system
  • Printed and online precinct and district maps for the public, candidates, and incumbents
  • Preelection planning such as polling place siting, delivery routing, and custom mapping
  • The Online Polling Place Locator, which identifies and maps a voter's polling place
  • Election night dynamic display of reported precincts
  • Postelection mapping and analysis of turnout and results
  • Accurate geocoding of the county's 1.5 million registered voters
  • Assistance to other government agencies around the state
  • Mapping and analysis to support county court cases
  • Participation in the city of Phoenix Summer Youth Work Experience Program through Arizona Call-a-Teen

One particularly noteworthy GIS application is the department's online mapping presence at At the ArcIMS-powered Web site, visitors can choose from several map viewers that range from a simple, one-click navigation viewer to a viewer with sophisticated navigation, display, and analysis features. This gives everyone access to political information—from first time Internet mapping users to more advanced users with more demanding requirements. More than 1,100 static, preformatted maps, created in ArcMap and saved in Adobe Acrobat PDF format, can be viewed online or printed.

The department has found the flexibility of ArcIMS to be particularly useful. The internal "Elections Department only" version of the Web site expands the data available to include possible polling places and click-and-report access to individual voter information.

The department's Polling Place Locator is available prior to elections for voters to enter their address to find out where to vote. This application alone received tens of thousands of hits for the November 2002 general election on election day and the day before.

During the redistricting of Maricopa County's supervisor districts and judicial precincts, an Internet application was provided that allowed users to sign up, log on, and draw their own redistricting plans using some of the sophisticated grouping and reporting features normally found in desktop redistricting software. This application was well received by a public eager to actively participate in the redistricting process. The county court system also used the application to examine jury pool demographics.

Finally, the department has partnered with the Arizona Independent Redistricting Commission (, the five-member commission chosen to redraw Arizona's legislative and congressional districts, to support the Web site and online mapping capability.

"I'm very proud of our staff and its accomplishments," said Maricopa County Recorder Helen Purcell. "Because of its creativity, the department's Internet applications related to redistricting received several awards in 2002: a Special Achievement in GIS Award from Esri, an eGovernance Award of Merit from the National Academy of Public Administration, and an Achievement Award from the National Association of Counties."

Another significant elections GIS application, and arguably one with the most impact on its internal work processes, is the integration of ArcView as an editor for the Recorder's Voter Registration System streets and boundaries tables. These tables store address ranges and alignments for streets and north–south–east–west address alignments for boundaries. The Voter Registration System uses the tables to code voters into the proper precinct and districts and to determine in which elections a voter is eligible to vote.

Prior to 1999, the department relied on hand-drawn graph paper representations of districts and printed reports of streets to determine how to manage these tables. This method had several shortcomings—the graphs were never to scale, frequently had to be redone due to annexations, and were difficult to draw and interpret correctly.

At the end of 1999, the department implemented an ArcView 3 application that models streets and boundaries and lets users actually see the relationship between the two. Although the database is only "faux" spatially enabled, the application enforces some topology rules in the tables. This application has easily saved hundreds of hours in maintaining and troubleshooting this critical piece of the system.

According to Purcell, the Recorder/Elections Department has even more in store for the future. "We have plans to extend our voter geocoding capabilities to get the most accurate precinct and boundary assignments ever," she said. With the new system, a voter's true x,y location will be used with a point-in-polygon function against the spatial representation of the boundary database to determine the correct district. This method is already used prior to elections to audit districts so that potential problems can be found and fixed.

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