The concept of parcel mapping goes as far back as ancient China, Egypt and Babylonia (Goodwin 1994, 20). In colonial North America, the most common techniques of keeping track of land ownership were surveying and deed registration, but not actual parcel mapping. As a result, prior to 1950 most towns in New England referenced land parcels within the town by Register of Deed's book and page numbers, subdivision map, or record plan rather than depicted groups of adjoining parcels on detailed maps. Since then, mostly due to increasing property values and rapid development, towns began to realize the importance of having accurate parcel maps and they started to invest in this area (Goodwin 1994, 21).
It is the proposition of this guide, that parcel maps are reference tools and do not replace deeds or record plans and the legal conveyance of a property either by boundary, dimension, or ownership. The utility of a parcel map is that it allows for easy identification of where a property is located relative to public ways and adjacent properties. For planners, assessors, and engineers it provides a construct to aid in the evaluation of proposed subdivision, compliance to local zoning, expansion of municipal utilities, and as a tool for managing the tax assessment process. A parcel map is perhaps the most convenient resource available to the public to determine the location and parcel identification number of a property.
An adequate parcel map should reflect size and shape of each individual parcel owned in a town. Many town officials (assessors, planners, engineers, and others) use parcel maps on a daily basis, that is why it is very important that parcel maps should show the most current and updated information. Development of computer technologies along with geographic information systems (GIS) created opportunities to conduct this work more efficiently. It is much easier to store, maintain and update a digital map than an analog paper map. Digital parcel mapping also simplifies the process of locating the information about any of the parcels and markedly reduces time necessary for making changes and printing new copies of the maps on paper. Digital maps can be connected to computer databases (such as a Computer Assisted Mass Appraisal (CAMA)) that allow access to and maintenance of valid records including valuation, ownership, and description. Digital parcel maps can be integrated into a more general geographic information system that will allow users to maintain and retrieve the record of zoning, land use, conservation easements, etc. Due to increased efficiency of tax map management and the potential for valuable GIS applications, many towns are transitioning from paper to a digital form of parcel mapping.
This document is prepared for the purpose of providing local governments with a comprehensive guide to tax parcel map conversion for use in GIS. All aspects of the conversion process are detailed, including methods, georeferencing, integration with CAMA databases, accuracy standards, and legal issues. Each chapter covers the basic concepts, issues, and methodologies. Software specific instructions are not included, although case studies are presented to illustrate how some Massachusetts communities use a variety of software components. The guide also includes a model request for proposal to aid local governments in contracting for parcel conversion.
Next Section: Mapping Methods Home