New Boston, Indiana.
New Boston is a city in the Confederation of Indiana. It is mentioned only once in For Want of a Nail ... , on p. 66, where Sobel refers to it and the city of Kent as "rising industrial and commercial centers" in the period between 1810 and 1840. There is no entry for New Boston in Sobel's index.
In For All Nails, New Boston is on the site of IOW Cincinnati, Ohio.