To determine a property with a town line as a boundary, the town bounds have to be surveyed, if any can be located.
Unfortunately, many of the town bounds have been disturbed or destroyed due to development and widening of roads. Most of these town bounds, if set at all, were set over 150 years ago. A lot has changed over that time!
Here is an example of a town bound I found today on the Lincoln and Smithfield town line.
You’ll notice the chiseled “L” for Lincoln on the east side of the stone bound and the chiseled “S” for Smithfield on the west side of the stone bound.