IN 1847, the Commonwealth of Massachusetts ordered that a line be drawn from the mouth of the Shawsheen River, down along its eastern bank, and “thence in a straight line westerly, to a marked stone in the wall … by Jacob Barnard’s house.” This formed the first two legs of the boundary of the new town of Lawrence, and it is this line, with some later adjustments, that still marks the division between the neighboring municipalities of Lawrence and Andover. 

Today, that same line represents one of the most striking socioeconomic divisions in the state. North of the line, residents of Lawrence earn a median household income of $44,613. South of the line, the median income in Andover is more than three times higher, at $151,334. Lawrence is about 53 percent white; Andover is 80 percent white. Only 1 in 10 adults in Lawrence has a bachelor’s degree or higher; in Andover, 3 out of 4 are college graduates. 

In the middle of the 19th century, Lawrence was an economic marvel, the site of the Great Stone Dam and the booming mill complex powered by the Merrimack River. Andover was an agricultural town of just a few thousand people, and setting the two towns apart on the map was both a practical response to how an industrial community should be governed as well as a handout to the interests of the factory proprietors who wanted to rule their own jurisdiction. Once drawn, though, a border is very difficult to un-draw. Andover and Lawrence were set on different historical courses, and those differences hardened into gaping inequalities more than a century later. 

Some dividing lines in today’s geography are even more antique than the one between Lawrence and Andover. The border between Woburn and Lexington dates back to the 1640s, when Woburn was still part of Charlestown and Lexington part of Cambridge. That means that an imaginary line drawn at a time when King Charles I ruled over New England still has a very real effect today: People living on the Lexington side earn, at the median, a little more than twice as much as those on the Woburn side. 

An overall map of the state can be useful for visualizing broad regional trends, like how Western Massachusetts is different from metro Boston, or how the 128 suburbs compare to the 495 suburbs. But with so many colors and symbols, a statewide map can actually be poorly suited for making specific observations about the differences between neighboring towns. These kinds of neighbor-to-neighbor comparisons—which highlight how things change when you jump from one side of a town line to another—oftentimes dramatically illustrate just how much geography plays a role in patterns of inequality. 

In the interactive visualization below, which is geographic even though it isn’t a traditional map, we can consider cities and towns in terms of their neighbor-to-neighbor comparisons.  (Click on “Instructions” to learn how it works and then explore communities across Massachusetts.) 

Editor's note: you are strongly encouraged to click through to the source and explore this resource, especially if you're from Massachusetts.

Divisions between mill cities and their adjacent dormitory suburbs offer some of the most striking contrasts in economic inequality amongst neighbors: not only Lawrence and Andover, but also Springfield and Longmeadow, Holyoke and Southampton, Fall River and Freetown, or Fitchburg and Lunenburg.  

Like Lawrence, many of these cities were set apart when they had a growing economic base of factories. When the Massachusetts economy shifted to service industries and personal wealth became ever more tied up in single-family homes, those same jurisdictional lines left these cities cut off from the landscapes of suburban affluence. 

Lines of racial division also set adjoining municipalities apart from one another. It’s hard to tell from a satellite view where West Bridgewater ends and Brockton begins, but when you cross that line you’re going from one of the least diverse towns in the state (96 percent white) to one of the most (36 percent white). Melrose was once a part of Malden until it was sliced off in 1850; now Malden is home to a population that’s 43 percent foreign-born, while only 12 percent of Melrose was born abroad.