Blue pup money. The slang name applied to the notes or circulating medium (substitute for
money) formerly issued by plank road companies—companies which constructed and maintained
plank roads and collected toll from persons who used the roads in travel or traffic. The notes so
issued were in small denominations, mostly for fractional amounts, and were ostensibly for use in
paying toll, but they freely passed current as money in the sections where they originated. They
are said to have first been issued in Indiana. They were called blue pup money to distinguish them
from red dog money, which name was given to notes of another kind and of larger denominations;
see Red dog money.