Normative Data Project for Libraries

Case Study with NDP

Mapping Our Service Areas

by Sherry Lee, Systems Librarian

Huntsville-Madison County Public Library

How We Began...
Our library automation vendor, the SirsiDynix, asked us to take part in a library data project in which libraries would be able to easily access their own library and patron use statistics. More importantly, the product would allow libraries to view and compare their own data with that of other library systems of a similar size. SirsiDynix was also partnering with GeoLib (the Public Library Geographic Database) to map out these statistics for library areas. Since we were participants, SirsiDynix and GeoLib asked us to take on the challenge of drawing out our service areas for each of our library locations. GeoLib would then enter our drawn service areas into their database and we could then view our patron use and library data in a mapped form. As a result, our library system could then develop an accurate perception of the "market" or "customer service" areas for each of our library locations. Being able to define such areas would allow us to effectively tailor our services and collections with our library communities and spend our funding more efficiently.

We agreed from the very beginning that we should map our library service areas as a group in order to incorporate more than one point of view. A committee was formed which included a variety of staff from Branch Managers, Main Library departments and Administration. The committee felt that such a mapping project would be easier if a draft map of the service areas was created. The group could then have a base from which to work and add or remove sections from each service area as they felt necessary. The task of producing such a draft map was given to me, Sherry Lee, the Systems Librarian who is responsible for the Library system's statistics and demographics.

Working From a Starting Point...
Originally, GeoLib requested that our map be drawn out based on census block groups, as that was the smallest range from which the data could be entered on their end. Finding a map of Madison County by census block group was more challenging than I expected. Our Reference Department here at the Main Library has census block group maps of the county from 1990 and prior. However, due to cuts in federal funding, the U.S. Census Department did not produce census block group maps in paper form for the 2000 census as they had in the past. I contacted the city and county planning departments and received many lectures on how printing out block group maps with street names for the county would fill up a high school gym. All I really wanted was a map of our county with street names and census block groups! Not wanting to go the high school gym route, I took a completely different path. Luckily, three years ago, the city of Huntsville created a GIS (Geographic Information Systems Department) for urban planning, etc. To quote their department information from the Huntsville City website:

"The Geographic Information Systems staff provides GIS data to city departments and to the general public in the form of maps, digital images, tabulation, document publications and webpages. Examples of databases maintained by the GIS division include, but are not limited to: zoning, city limits, wetlands, floodway/ flood fringe, slope development districts, landslides, geology, storm water infrastructure, sanitary sewer systems, bridge inventory, warning sirens, soils, greenways, open space, parks, drainage basins, recreation leagues, City Council districts, historical districts, air quality monitoring, land use, fire districts, traffic calming and inspection zones."

This department was extremely helpful to me. The GIS staff printed out a wide variety of census block group maps upon my request and worked with me in every way possible to provide the maps that I needed at no cost. Some maps showed the entire county with block groups and street names. Other larger maps were close ups of streets and block group areas. These larger maps were beneficial for zooming in on the downtown city block groups which were smaller and tighter in layout. Additionally, GIS printed maps with county commissioner, city council and school board districts so that we could view political as well as funding boundaries. These GIS maps were not only highly beneficial to the service area mapping but also will be very useful for our other HMCPL projects.

We also received several copies of a large detailed street and Zip code map for Madison County from the Huntsville/Madison county Chamber of Commerce. These street maps allowed us a familiar base from which to start in viewing landmarks and geography throughout our region. The GIS and Huntsville/Madison County Street maps were laminated so that they would hold up to frequent use and could be used with erasable markers.

Determining Patron Use...
As the library statistics and demographics person, I decided to create a map based on library usage from which the committee could work. The group members were already familiar with the political boundaries of the county but had never seen our patrons' usage patterns mapped out before.

Huntsville-Madison County Public Library uses SirsiDynix's WorkFlows version 2003.0.11.1 for our library's automation. WorkFlows has a variety of canned reports that we can utilize to determine patron use as well as item circulation and statistics. One of the most useful of these system reports is a "transaction statistics report." This report can compile and sort checkouts, renewals, etc. at a selected library location by patron Zip codes. A patron's Zip code is the smallest geographic point on which transaction statistics reports can be run through WorkFlows.

Prior to this project, I had spent several months compiling census and patron use information for each library location to complete a "Demographic Report-Patron Profiling" for HMCPL. I determined that there were approximately 54 Zip codes in and surrounding Madison County that might use the our libraries. These Zip codes were compiled simply by looking at Zip code maps of Madison County and the surrounding counties of Limestone, Morgan, Marshall and Jackson. I selected any Zip code that was in Madison County or anywhere close to the county line. Huntsville-Madison County Public Library does allow out-of-county residents to obtain a library card for an annual fee of $15 for an individual or $25 for a family membership. Next, I created a list of these 54 Zip codes and a geographic description for each using such websites as and to determine the exact location. For example,

"Zip Code 35811-Northeast Huntsville-east of Highway 231 North and north of Oakwood Avenue including I565 East/Highway 72 to Chapman Mountain."

In this way, everyone would have an accurate picture of where each Zip code was located. These Zip codes were then entered into the transactions statistics report and reports on patron checkouts were run for each library location. Those Zip codes that had the highest use of the 54 Zips were selected as the "top use Zip codes" for that library. Please see the chart below for more detail:

Top Patron Use-Hazel Green Library

Total circulation for 2004 budget year: 39,442
Zip Code Circulation (for 2004 budget year) % of Hazel Green's Total Circ.
35750 23,525 60%
35759 4,705 12%
35761 4,096 10%
35773 3,366 9%
37334 794 2%
35810 654 2%
35811 491 1%
35805 466 1%

Other measures such as items transited reports for each library, patron and staff interviews, and first-hand observations were used to further validate patron activity at each location.

Creating a Draft...
Once the usage reports were run and compiled, I studied the detailed street map of Madison County as well as the block group maps and compared the usage data with the areas around each library. I took a close look at the Zip code boundaries and where they fell in regard to the census block groups. The geography and road access of each area were also important considerations. Patrons might be less likely to travel a route to a library that was a 2-lane road over a mountain if they had equal access to a main highway with four or more lanes. I looked at traffic count maps and charts which are made available to the public through the city of Huntsville's website. With all the factors of usage data, Zip code boundaries, block groups, geography and traffic in mind I began drawing out the usage service areas for each location one by one.

First, I made easy to read colored name labels for each library location and placed them on the block group maps. Additionally, marks for each library were also made on the street maps. I kept each service area to census block group boundaries and used a different color marker for outlining each area. The process was not as simple as just drawing out each service area according to how the block groups group fell within each Zip code. Some of the block groups for Madison County were quite large and crossed more than one Zip code. Adversely, some of the Zip code areas that utilized library locations had portions that extended into other counties or were completely out of a reasonable access range to the library. Each completed usage service area was a compromise of all of these elements including geography and road access.

Defining a Service Area...
The "Service Area Mapping" committee agreed to set aside a day to work on the final copy of our service areas. Since we have 12 locations throughout our system, we wanted to allow plenty of time to review each location.

My supervisor and the head of HMCPL's Internet and Technology Department, Melissa Shepherd, had also run a wide variety of patron use reports for another project. Her reports focused on patron library (i.e. where the patron originally registered for a library card) cross-referenced with Zip codes and transited item statistics. Based on the report results and her knowledge of the county as a lifetime resident, Melissa drew out her own perception of each library's service area on the detailed street map. Geography and road access also played strong roles in her concept of each area. Melissa's version and my version of the maps were similar in that usage was a primary component. As a result we now had two separate maps, one by block group and one by streets, from which the committee could work.

When the committee met, we first had to address the following:

What is a service area? How does one define a service area? Is it based on patron or customer use? Is it limited strictly to one's proximity to a location? Is there a generally accepted mileage radius that would automatically define the service area for each site regardless of any other factors? What about the political districts of which each library was a part? For example, our locations are also defined by the county commissioner district in which a library is located and a percentage of the library system's funding comes from these types of political resources.

These were the kinds of questions that we asked before putting erasable marker to laminated map. We all agreed that patron use was a critical element in determining a service area. Also important, since part of our library system's funding was dependent on county commissioners, the City of Huntsville, etc., the political boundaries could not be discounted. Ideally, the political boundaries and the patron usage boundaries would have matched and we have could accurately displayed use and political funding in one map. However, incorporating these elements involved a compromise because of the differences between the two.

The patron usage map that I drafted showed a tremendous amount of overlay in the service areas. We expected this as usage statistics and the compiled "Patron Profiling" demographic reports indicated that patrons of Madison County were willing to travel to obtain the library materials that they wanted. Such reports showed that patrons often used more than one library. We also found that our patrons did not singularly use the library that was closest to their residence. Demographic, use reports, patron and staff interviews, revealed that our patrons had time constraints, as many people do these days. They were using libraries, even possibly those that were on the opposite side of the county from which they lived or worked, because that particular location was near where a child had gymnastics lessons, or shopping areas, etc. The committee felt that the usage areas portrayed in the draft were accurate according to their own experiences with patron use.

The political boundaries, on the other hand, were very different from the usage areas. For example, some of the commissioners' districts encompassed more than one library. Also, of course, the political districts and city limits of the towns throughout the county do not overlap. Additionally, because we are a county cooperative system, we have some library locations within the City of Huntsville limits and some locations in other towns or unincorporated parts of the county. As a result, some libraries receive county and municipal funding while others receive purely county funding.

We composed definitions for each of these service area types as follows:

Measuring Services

For the purpose of measuring services, two different geographic models will be defined: legal service areas and areas of usage.

  1. Legal Service Area - the legal service area is based on political boundaries. The primary factor determining the extent of a legal service area for a location will be based on funding sources for the satellite or library within that zone. The primary boundary for the library system is the county line itself. All services to county libraries originate from the Main Library which lies within the Huntsville city limits. The Main Library's legal service area overlays all services areas of all satellite locations. The libraries which are considered satellites (all libraries but Main) have at most two sources of funding from within Madison County; county funds from commissioners in whose district the location lies and any overlapping municipality.
Library Municipal
Main Yes Yes Yes
Madison Yes Yes Yes
Bookmobile Yes Yes Yes
Bailey Cove Yes Yes Yes
Eleanor Murphy Yes Yes Yes
Bessie K. Russell Yes Yes Yes
Oscar Mason Yes Yes Yes
Showers Yes Yes Yes
Monrovia No Yes Yes
Hazel Green No Yes Yes
Gurley No Yes Yes
New Hope No Yes Yes
Triana No Yes Yes

Legal service area borders of satellites are therefore subsets of the Main Library system's service area. The borders are necessary compromises between the funded geographic areas surrounding the satellite and patron usage patterns. In light of this, it might be expressed that all satellites in the county (with the exception of Madison which holds its own in municipality funding) are in fact service outlets placed to accommodate usage patterns. The legal service area of Madison County makes no provision for out-of-county card holders as they do not support the library in any other way fiscally than a $20.00 per year fee.

  1. Usage Area - Each location of the Huntsville-Madison County Public Library has its own distinct usage area. Every usage area overlaps and contains the same Zip code set. All usage areas extend beyond county boundaries because of non-county residents who are card-holders. The usage area for each satellite is comprised of all Zip codes and is expressed in terms of percentage of circulation at that satellite from patrons of each Zip code, i.e. what percent of patrons in the 35811 Zip code checkout items from the Hazel Green Library.
Top Patron Use-Hazel Green Library

Total circulation for 2004 budget year: 39,442
Zip Code Circulation (for 2004 budget year) % of Hazel Green's Total Circ.
35750 23,525 60%
35759 4,705 12%
35761 4,096 10%
35773 3,366 9%
37334 794 2%
35810 654 2%
35811 491 1%
35805 466 1%

The primary determining factor in establishing a service area are circulation and transit counts at each location cross-referenced by patron Zip codes. Manual measures such as patron and staff interviews and observations are used to further validate this measure and warn of discrepancies.

Library Number of Transited Items (for 2004 budget year) Circulation (for 2004 budget year) Circulation from Out-of-County Zip Codes Percent of Use from Out- of-County Zip Codes
Main 157,170 787,356 29,365 4%
Madison 45,154 380,385 6,403 2%
Bookmobile 1,419 7,794 111 2%
Bailey Cove 47,575 247,776 5,269 2%
Eleanor Murphy 21,687 56,690 4,170 7%
Bessie K. Russell 7,357 25,651 146 1%
Oscar Mason 2,399 6,374 87 1%
Showers 1,732 4,242 19 Less than 1%
Monrovia 11,080 49,128 271 1%
Hazel Green 6,352 39,442 1,498 4%
Gurley 1,910 11,083 782 7%
New Hope 2,007 19,310 1,129 6%
Triana 78 388 0 0%

The Final Results...
In comparing the legal and usage service areas of each library location, the two maps exhibited a variety of strong similarities as well as stark differences:

Seeing our legal and usage areas laid out on a map was highly beneficial to our library system. As a result, we now have a clearer picture of our political funding and patron activity. This provides us with a new opportunity to ask vital questions regarding our use, funding and services and to improve the allocation of our library system's resources.