There are two species of striped snakes in New England, the Common Garter Snake and the Eastern Ribbon Snake (Thamnophis sauritus). One way to tell the two apart is to note the location of the light-colored side stripe. If the stripe occurs on scale rows 2&3 (counting up from the belly), then you've got a Common Garter Snake. If the pale stripe is on scale rows 3&4 (see Quiz #162), then you've got an Eastern Ribbon Snake.
The Eastern Ribbon Snake is slender with a long, thin tail and total length of 1.5-3'. Also, note the narrow yellow mark just in front of each eye. To learn about this species' habits and life history, visit Animal Diversity Web. And, the next time you encounter a snake with whom you're unfamiliar, take some pictures or make a quick sketch, and then consult the simple key on the Snakes of Massachusetts website published by UMass Amherst.