1830 Massachusetts Map Viewing Instructions

The following is a excerpt from the 1830 project methods documentation file which the user is strongly suggested to read in its entirety.

The Massachusetts 1830 map series represents a unique data source that depicts land cover and cultural features during the historical period of widespread land clearing for agriculture. To our knowledge, Massachusetts is the only state in the US where detailed land cover information was comprehensively mapped at such an early date. As a result, these maps provide unusual insight into land cover and cultural patterns in 19th century New England.

However, as with any historical data, the limitations and appropriate uses of these data must be recognized:

1. These maps were originally developed by many different surveyors across the state, with varying levels of effort and accuracy.
2. It is apparent that original mapping did not follow consistent surveying or drafting protocols; for instance, no consistent minimum mapping unit was identified or necessarily consistent among surveyors; as a result, whereas some maps depict only large forest blocks, others also depict small wooded areas, suggesting that numerous smaller woodlands may have gone unmapped in many towns. Surveyors also were apparently not consistent in what they mapped as 'woodlands': comparison with independently collected tax valuation data from the same time period indicates substantial lack of consistency among towns in the relative amounts of 'woodlands', 'unimproved' lands, and 'unimprovable' lands that were mapped as 'woodlands' on the 1830 maps. In some instances, the lack of consistent mapping protocols resulted in substantially different patterns of forest cover being depicted on maps from adjoining towns that may in fact have had relatively similar forest patterns or in woodlands that 'end' at a town boundary.
3. The degree to which these maps represent approximations of 'primary' woodlands (i.e., areas that were never cleared for agriculture during the historical period, but were generally logged for wood products) varies considerably from town to town, depending on whether agricultural land clearing peaked prior to, during, or substantially after 1830.
4. Despite our efforts to accurately geo-reference and digitize these maps, a variety of additional sources of error were introduced in converting the mapped information to electronic data files. Thus, we urge considerable caution in interpreting these maps.

Despite these limitations, the 1830 maps present an incredible wealth of information about land cover patterns and cultural features during the early 19th century, a period that continues to exert strong influence on the natural and cultural landscapes of the region.

Citation of Datalayers

Harvard Forest. 2002. 1830 Map Project. Harvard Forest Archives, Petersham, MA.

Hall, B., G. Motzkin, D. R. Foster, M. Syfert, and J. Burk. 2002. Three hundred years of forest and land-use change in Massachusetts, USA. Journal of Biogeography 129: 1319-1135.

Data Layers

Harvard Forest is making the datalayers from the 1830 map series available for online viewing through ESRI's ArcIMS. This is a program that allows viewers to turn features on and off, zoom in, print, perform simple queries of data, etc. A USGS topographic map (from MassGIS) can be turned on as a background

To view the legends for a particular layer

1. turn the layer on by checking the "Visible" box
2. click "Refresh Map"; always click "Refresh Map" after changing a layer's visibility. (Figure 2 below)
3. click the top left button to the left of the screen ("Toggle between Legend and Layerlist") (Figure 1 below).
4. click "Toggle between Legend and Layerlist" again to go back to the previous screen to make other layers visible.

To save the map as an image

The viewer does not allow direct saving of the map to an image file, so users should press the print screen key on their keyboard and paste the image into the program of their choice.