Population density is a standard yardstick of development, but assessing it is trickier than it seems. According to the standard measure of density, communities in southeastern Massachusetts seem to have a lot of elbow room (see smaller map). For example, as of early 2000, fast-growing Plymouth was still more sparsely populated than the MetroWest suburb of Weston, with 0.84 people per acre vs. 1.06 people per acre, making it seem like a textbook case of land-gobbling sprawl. When considering only the parts of communities where people could live, however, the South Shore was no different than the rest of metropolitan Boston, with only a few towns standing out for large gaps between houses. As shown in the larger map, if you count only land that is zoned for residential use—ignoring such things as office parks, retail districts, recreation areas, and cranberry bogs—Plymouth, which covers more land area than any other city or town in the state, was more than twice as crowded as Weston. Under the switch to “real” density, America’s Hometown rose from 172nd to 113th in population density among the state’s 351 communities, with almost exactly 5.0 people per acre. Weston, with only 2.4 people per acre, fell from 148th to 253th.
While 29-people-per-acre Somerville was the most densely populated community in Massachusetts overall, Chelsea took that title, with 67 people per acre, after subtracting the 33 percent of the land area zoned for industrial use (the highest such percentage in the state). Taking out the part of Provincetown that falls within the Cape Cod National Seashore, that community rose from 208th to 66th in density. Conversely, Arlington, a suburb west of Boston, falls from 12th to 20th because it ranked first in the share of its area zoned for residential use (75 percent) and had little land to exclude when figuring real density.