Implementing ArcGIS 8.1 for Redistricting

Bob Andrew, GIS System Architect for DynCorp Information Systems on the project
with Larry Boden, Manager of Technical Operations at Esri Implementation Services

 DynCorp Information Systems, LLC (as system integrator) and Environmental Systems Resources Inc (Esri as developer) designed a major upgrade at the Department of Justice (DOJ). This provides a richer, faster, more manageable system for DOJ to perform its responsibilities under the Voting Rights Act. The paper describes "lessons learned" in going from UNIX workstations to Windows NT desktop, from ArcInfo 7 with coverages and shapefiles to ArcInfo 8 and ArcSDE with Oracle database.


The purpose of this paper is to illustrate improvements for end-users in GIS technology that has moved from workstation to client-server and in spatial data design from shapefiles and coverages to a geodatabase. The project used to illustrate this at the time of publishing this paper was still in the final stages of development, so functionality discussed and illustrated may not be in the final product.  The 2000 decennial census was a major business driver for all providers of redistricting tools to closely examine their processes and software - this is just one of three stories you will hear in this afternoon's session entitled "Redistricting Using Census Data".

Redistricting Review

Under Section 5 of the Voting Rights Act of 1965, jurisdictions in 17 16 states are required to obtain preclearance for any voting change, including redistricting plans that they enact. One option for obtaining such preclearance is to submit it to the Department of Justice for its review. In those instances, DOJ is required to respond within sixty days of receiving any submission.  The geographic data contained in the submissions usually include at least a paper map of the proposed redistricting plan. In addition, the Department allows a jurisdiction to submit an electronic list , or "table of equivalencies," of county, census tract, block group, or block and the electoral district to which each is assigned. DOJ Plan Preparation staff have a role to ensure a proposed map and the "equivalency table" match up without geographic slivers or numeric errors. Once the geographic assignments and resulting GIS map are verified as being accurate, the proposed redistricting plan is analyzed to determine whether it meets the standards of federal law.

Former GIS System

A decade ago, DOJ Civil Rights implemented Unix-based system to perform most of the necessary mapping and statistical steps required to analyze any proposed voting district boundary changes arising from the 1990 Census. This used individual workstations and a  single server to store all plans for redistricting, plus Census attribute and geographic data. In the mid-1990's the same application was upgraded with some faster Unix workstations and additional servers.

Reasons to Change

 The existing system was very slow to re-draw large plans, as well as it required specialized GIS staff to maintain the software and hardware. Even small changes to the application required substantial effort. The hardware was also close to or beyond its life expectancy. Moving to an interface running on a standard DOJ desktop system would avoid users also needing specialized workstations, saving in capital and maintenance. Note DynCorp I.S. staff were already onsite working at DOJ implementing an upgrade of their Office Automation Systems.

Following an internal pilot on the beta of ArcGIS 8.0, DOJ contracted with DynCorp I.S. to work with Esri Implementation Services to develop a user interface, this time using ArcGIS 8.1, which in 2000 was just going into beta. DOJ committing to develop with the core new technology enabled the development staff to take advantage of new features planned for ArcGIS 8.1 and for DOJ to prolong the shelf life of their tools.

Design Approach

DOJ's attorneys, analysts and onsite GIS staff had already determined a core list of requirements for the interface design, based on review of their existing system, plus functionality that was available in 1999 through commercially available redistricting software. A key objective was to use core  technology wherever possible: so DOJ Civil Rights Districting Extension (DX), a custom user interface to ArcGIS was developed.

What was not specified in a requirements list built from a user-interface perspective were vital data modeling steps -  these impacted both schedule and the design. This project used the strict discipline of an integrated geodatabase model, rather than separate shapefiles and coverage models. This approach is more sustainable over time in the evolving process of redistricting.

Project Schedule

Esri and DynCorp planned to divide these requirements into three phases: a client-only release; a client-server release that worked with 1990 data; and a release to work with Census 2000 data. In third quarter 2000, right after reviewing a conceptual design prototype at the Esri International User Conference, the original requirements were broken down into a detailed design matrix spreadsheet of some 170 implementation tasks. This spreadsheet was used monthly throughout to manage design progress against the tasks and phases.

System Platform

Prior to DynCorp taking on the system integration responsibilities, DOJ had contracted with Dave Peters, Manager of Esri Systems Integration, to conduct a  strategic plan for system architecture, using bench-mark performance data of Unix and Windows/Intel platforms to aid in sizing servers for ArcSDE/Oracle.

DOJ chose to stay with the proven performance of Unix, and now have two mid-range Unix servers and a variety of mass storage, backup and archiving devices all dedicated to aspects of Civil Rights GIS (which is broader than just the Voting Rights usage featured in this paper).

For client hardware, ArcGIS 8.1 is deployed on the same high-end Windows NT desktops as the rest of the office automation software, thus eliminating DOJ's need for any special GIS workstations Using Windows NT in a managed network like DOJ's is a challenge, because of the complexity of Administrator rights vs. local user rights, and because the Esri design team were already all on Windows 2000. The impact is more extensive onsite testing required within the office automation environment.

The Districting Extension (DX for short) is principally client-server. Given the magnitude of the Census 2000 data modeling and client-server ArcGIS/Oracle design effort, DynCorp recommended against going with a web implementation at this stage, such as ArcIMS 3.x, but the extension does produce XML metadata of redistricting plans and a JPEG of the plan, which could be used within ArcCatalog and a simple intranet web service. (In hindsight, given that ArcIMS 3.1 was only just released June 2001, sticking solely with ArcGIS was still the right choice for this project at this time).

Data Modeling

The commitment to geodatabase also required disciplined modeling of all the data structures and processes required in districting. One good example that can be visually demonstrated is the data modeling required to support the four demographic levels of geographic resolution: county/tract/block group/block. The DX has tools to be able to drill down to selected level of resolution. For example, to select a district comprised of a number of tracts plus several block groups. The tools can show in more detail e.g. just the block groups of a selected tract, while leaving all the other geography in a districting plan at the tract level. This has value for performance reasons (not having display every tract at the block group level), and is less visually cluttered. The data model also supports the "join" necessary to display the selected district with a single boundary and display the associated statistics.

Database Design

Oracle 8i was the chosen platform for this project. The DX data model is implemented as state-by-state data storage in Oracle tables, supporting all key Plan Properties required of all submissions as published in the Federal Register in compliance with OMB guidelines. Census 2000 geographic and population data is also stored using this same data model, so although content is identical to that published by Census, for performance reasons it is structured to suit the purposes of DOJ. With the completion of this Voting Rights application, on-site GIS staff will be able to take advantage of the same core data for other Civil Rights applications.

Application Performance

Since GIS is inherently demanding on bandwidth, one part of the design effort concentrated on removing the need to re-draw the screen with changes in district boundaries, even minor ones. Techniques were developed to highlight selected geography prior to committing a boundary move. Similarly, to avoid unnecessary server processing, a preview of statistical changes before the commit step. In an effort to further reduce network traffic, an endeavor was made to do all DX analysis work in the client-side personal geodatabase, but with several key steps requiring server-side polygon joins, for performance reasons this decision was revisited and all plans are now worked from the Oracle geodatabase on the server. Given the uncertain fate of personal geodatabase in its present form as ArcGIS looks ahead to Release 9, this again was probably a prudent move. It is fair to say that the team devoted to this project had a major impact on the functionality that made it into ArcGIS 8.1 and ArcSDE 8.1

User Interface

Considerable effort was applied to ensure the end-user had intuitive access to the entire districting process and workflow. Techniques like "dockable windows" ensure that windows plan layers, plan statistics and plan maps are consistently tiled, with users able to set the relative size of each window.  Custom floating toolbars and custom ArcMap icons are used for many of the most commonly repeated tasks. Use of icons even extends to a customization of ArcCatalog where colored flags indicate the status of a particular plan - checked out for review, stored on server, on local hard drive etc.

In the years following the release of the decennial census data DOJ expects to receives over 3000 redistrictings plans to analyze under Section 5.. Managing the submissions can be almost as daunting of a task as actually reviewing them. For this, ArcCatalog was extended to support the redistricting plan management system.

The DX uses the power of ArcCatalog’s metadata tool to track plans. ArcCatalog creates metadata for each plan in an Extensible Markup Language (XML) file stored locally or on a Web server depending on if the plan is being edited locally or resides on the server for the user to retrieve for editing. The user also has the ability to create a new version of a plan to edit. In ArcCatalog, users can search for, preview, and explore plans. Thumbnails of individual plans are created to provide the user a quick overview of the plan.

Usability principles are still being applied in the final acceptance stages to important details like color palette, line weight. The DX will have the agreed set as defaults, with ability by on-site GIS staff to update these as required, as well as for users to define and store some personal preferences.

Modular Design

Core ArcGIS provides a rich set of ArcTools for use in such user interfaces. The entire DX interface is written as 28 modules (executables and DLLs) that enable parallel development and independent testing. Many of these modules are devoted to ensuring consistent use by whomever is assigned to do plan creation, editing analysis or review.

Concluding Remarks

The lessons learned are not new nor unique, and given that the interface is still in development we cannot fully claim that these are good lessons, but what we can say, so far, is that data modeling is of great significance, that well-defined requirements are essential, that the modular approach to development is important, and most of all, that methodical project planning and testing is a required ingredient.


Thanks to U.S. DOJ Civil Rights for the honor and opportunity to develop a new Redistricting application for the Voting Rights section.

Voting Rights: Bob Berman and Bob Kengle. Admin: Doug Crain and Nancy Sweesy
Onsite GIS: Mario Lopez-Gomez with Jonathan Brooks, Lou Summers,  Sharon Thomas

Esri Account Manager: Todd Rogers, now Civilian Federal Manager (& DOJ Account Rep).
Development: Larry Boden with Ryan Bae, Justin Fan, Craig Ferris, Kevin Kelly, Mike Redpath

OnSite Support: Steve Ciampichini, Fatima Awad, Jim Anderson, Josh Blue, Jim Correll, Spencer Crim, Sean Cononie

DynCorp Information Systems Management: Doug Cheek with Kevin Bell, Soo-Ung Kim, Bill Pratt, Lucian Russell

Robert D (Bob) Andrew
(now GIS Team Leader
with ICF Consulting Inc)