Places to Look

Town Meeting Records
Selectmen's Records
"Road Book"
Miscellaneous Files
Research done by Others
Town History
Historical Society / Library

Even though the most likely location for old road layouts is the town meeting records, you can't limit your search to those books. Sometimes towns allow the selectmen to "lay out" the roads, so their minutes need to be reviewed.
Some towns have created special "Road Books" where they collate road actions, but even if you find one, don't assume that is where all road records are stored.
In more recent decades road records may have been studied by others, so its always a good idea to find out if someone else has already done road research. Ask various Town Offices if they have a "Road" file.  You might find one in the Listers Office, or the Town Planning Office. You'll be delighted if you find a 1986 "Old Roads" research project by a former town historian (and very dissapointed if you find it AFTER you have spent 100s of hours repeated old Bob's research!)

Locations

1) Town meeting records. Usually large leather-bound ledgers of handwritten meeing minutes.

2)  Town “Road Book” or file .  Some towns keep separate road books.

3)  Research done by others -  Ask the Town Planner, the Listers, and the Selectmen if they have any file folders related to roads.  The work you are starting today may have been done before!

4)  Town Highway Department records.  Legal documents shouldn’t be at the highway garage, but they might be. Check there!

5) Your local library or historical society. Documents may have been transferred to them (though they shouldn’t be).