Are questions like these of interest to your community?

• Where are the most productive agricultural soils in town located?
  
• How many acres of the best soils are on land zoned for development?
  
• How many different owners hold land that is not in current agricultural use but is in an agricultural district?
• Which property owners must be legally notified because they are within the mandated distance of a 50 acre parcel proposed for subdivision?
  
• What is the mix of land uses on properties within 500 feet of locally identified unique natural areas?
  
• Where has recent development within a watershed occurred on highly erodable soils or steep slopes?
• What is the total assessed value of nonresidential property proposed for inclusion in a new commercially zoned district?
  
• What proportion of a town's residents are within a 10 minute drive from a proposed new town hall?
  
• What is the emergency vehicle response time to every structure in the city?

GIS

Geographic Information Systems, or GIS, offer a large and growing capacity to answer these and similar questions quickly, efficiently, and easily. GIS is revolutionizing the ways in which geographically based or mapable information is stored, accessed, analyzed, displayed, and made available to the public.

With GIS, both natural and built features of a landscape can be easily represented and visually displayed as points, lines, or bounded areas on a computerized map. Each represented feature, say a road or wetland, a farmhouse or a census tract, can be linked to extensive data sets that describe the feature - size, assessed value, census data, species diversity -- whatever is pertinent and available.

When mapped at the same scale, the spatial relationships between features are easily calculated. For example, a GIS analyst can easily evaluate and display distance relationships, such as generating a map or list of all homes within walking distance of a school or bus route. The analyst can just as easily identify areas where different features overlap. An example might be all areas within a county that have both high concentrations of poverty and a majority of homes that are more than 30 years old. The digitized features of a landscape (e.g. roads, houses, wetlands) may be displayed independently, one feature at a time. These "interpreted" features may also be usefully overlaid on uninterpreted images such as high resolution aerial photographs.

Using GIS software, one can zoom across map scales almost instantaneously. Thus, county wide maps and summary information can be displayed at one instant, while a map and data about a single neighborhood or parcel can be highlighted a moment later.

How can GIS be useful?

For many years, the usefulness of GIS was limited by factors like the cost and complexity of GIS programs and hardware in addition to the scarcity of useful or affordable GIS data sets. In recent years, exciting new geo-referenced data sets have been made available, often online at no cost, at the same time that advanced GIS and computer technology has become more affordable. It is also becoming increasingly easy to scan or otherwise enter specialized or local data and maps. After the initial investment, GIS can dramatically reduce the cost of storing, amending, rescaling, and reproducing all kinds of maps for citizens or clients.

Admittedly, GIS remains complex and costly enough that it is still not easily accessible to the casual user. Ongoing developments in web-based access to select benefits of GIS technology will continue to help break down this barrier. In the meantime, GIS is rapidly becoming an indispensable tool applied in many ways by local governments, professional planners, business and market analysts, academics, and neighborhood activists alike.

Community and local government based uses include the storage, display, retrieval, analysis, modification, and printed reproduction of such things as tax parcel data and maps; comprehensive land use plans; sites issued municipal building permits; important environmental areas and toxic waste sites; prime farmland; zoning maps; public transportation routes; dangerous traffic intersections and much more.

Businesses use GIS for a variety of market analyses, for example to evaluate whether or not there is a large enough nearby population with favorable demographic characteristics to support a new retail store at a given location.

Neighborhood organizations are working with local planners to map and better understand the relationships between their vision of a quality community and key features of their neighborhoods - historic structures, schools, busy roads, grocery stores, parks, abandoned gasoline storage locations, high crime areas, and so forth.

Academics and consultants are increasingly incorporating GIS tools into sophisticated models of how local growth management policies influence land use and patterns of development over time, or how land use changes impact water quality, or how animal migration routes are affected by human activity.

(for a review of many models, see Projecting Land Use Change: A Summary of Models for Assessing the Effects of Community Growth and Change on Land Use Patterns.)

Cornell, for example, recently used GIS to identify productive farmland and then simulated the amount of land that might ultimately be "built out" under a proposed farmland protection plan. For another multi-town region, we used GIS to map parcels that had characteristics most suitable for long-term agricultural use and that were simultaneously most likely to experience future development pressure.

How GIS can help communities

The reality is that the application of GIS to real life problem solving and public benefit is still in its infancy. Future applications are limited only by our budgets and imaginations. As with all information technologies, concerns about how GIS might be used, for example by creating new ways to access personal information, must be carefully considered. However, there is little doubt that GIS will become an increasingly important tool in the tool-box employed by people interested in strengthening local communities.

For more background on the basics of GIS and applications, see the following web sites.

US Geological Survey- good general background, natural resource applications

Cornell City & Regional Planning- Web-interactive environmental justice application

City of Ithaca - interactive parcel maps, municipal application

Cornell Institute for Resource Information Systems (IRIS) - resources - resource inventory, remote sensing, and geographic information systems.

Cornell University Geospatial Information Repository - GIS data source

National Geospatial Data Clearinghouse - GIS data source

New York State GIS Clearinghouse - GIS data source

Penn State University - Chart of the World - GIS world data

MapInfo - vendor

ESRI - vendor