Towns of all sizes can be walkable, there just might not be as many things to walk to.

Some examples include

• most college towns (and of course the colleges themselves)
• towns built out before the car - here in New England we have many

My town is very walkable, although it does have 60,000 so is not that small. We also have two colleges where the campuses are walkable but no real college town and two train stations, with a third planned. Does it “become a city” because we zone to allow five story apartment building near the train station at the town common?