What is Geographic Information Systems (GIS)?

In this week’s Q&A, we take a deep dive with Assistant Director of GIS, Neil MacGaffey, to learn more about the Commonwealth’s mapping tools and capabilities.


Q: What is MassGIS?

A: MassGIS is the go-to source for comprehensive statewide geospatial (maps and associated descriptive information) data. These public records are made available through on-line maps, web mapping services, and via data download. The resources available through MassGIS are the envy of most other states.

Q: What is Geographic Information Systems (GIS) and how does it work?

A: A Geographic Information System (GIS) is a computer system used for assembling, storing, manipulating, and displaying geospatial data. A GIS consists of computers, desktop or web-based software, data, and the people who use these tools to analyze and present this information. GIS data includes map features (typically referred to as “map layers”) such as roads, property parcels, fire stations, soils, parks, surface waters, etc, and associated descriptive information such as road type, property owner, soil type/characteristics, park owner, etc. The GIS database also includes air photo images as base maps. Using GIS tools, people can answer questions such as “what properties are within 300 feet of this road?” or “how many structures are in the area that was flooded?” Combining map information from different sources, these types of analyses typically identify relationships or geographic patterns that inform decision making. Results are often, but not always, presented on a map.

Q: Who uses GIS in the Commonwealth?

A: As part of Tech Services & Security, MassGIS serves a broad constituency in both the public and private sector: emergency response, real-estate research, environmental planning and management, transportation planning, regulatory oversight, economic development, development review, and engineering services.

Q: How do constituents actually use GIS mapping information?

A: Constituents access and explore MassGIS’ extensive library of mapped features using OLIVER. OLIVER is MassGIS’ primary on-line interactive mapping tool. Using OLIVER, people can create a map for any area of Massachusetts displaying the map features they select. MassGIS also provides other web maps that display specific themes such as Legislative Districts, shoreline change over time, and map information required for assessing and remediating contaminated properties. MassDOT manages and reports on the state highway system using GIS. Environmental Affairs completed statewide analysis of prospective sites for wind power generation on state-owned land. The Mass. Emergency Management Agency provides a map-based common operating picture for the Boston Marathon; The State 911 Department’s Next Generation 911 system uses GIS to route 911 calls to the correct dispatch center. Engineering companies use GIS to search for prospective solar farm locations, for pre-development analysis and planning, and for providing required map information to government agencies. Environmental consultants can review wetlands, topography, soils, and other information relevant to proposed developments. Municipal staff can review mapping of their communities using MassGIS’ free municipal viewer. These examples are just scratching the surface.

Q: How long have we been using GIS? How has this system developed since it began?

A: MassGIS originated in 1988 as a project within the Department of Environmental Protection. The project’s purpose was identifying sites suitable for low-level radioactive waste disposal. Sites had to meet many criteria including not being in sensitive areas (e.g., groundwater recharge areas), not being near residential areas, proximity to roads, and having a minimum size; no acceptable sites were found. Having demonstrated the value of GIS technology, MassGIS became part of the Environmental Affairs Secretariat Office. Shortly after, mapping and analysis by MassGIS demonstrated that proposed regulatory buffers along tributaries of the Quabbin Reservoir impacted much less development than people feared; this analysis was instrumental in the successful passage of the Watershed Protection Act. Then about 15 years ago, MassGIS was on the leading edge nationally in making its database widely accessible via industry standard web mapping services. Today, with the ready availability of extensive geospatial data and services the potential for deployment of the state’s geospatial resources is almost endless.