Interpreting Congested District or Business District Maps
A valuable feature in the prefatory material of editions for large
cities is the map of the "congested" or "business" district.
This kind of map was drawn at scales intermediate between the large
scale of a single sheet and the small scale of the key map for
a volume. A typical map of this type might cover an area twenty
blocks by thirty blocks in size. Generally, such maps served as
a frame of reference for understanding the relationship of buildings
and places in the heavily developed portions of towns. In some
cases, they were annotated to show the limits of coverage by fire
departments (in the early years of fire protection, fire company
service was not provided to all parts of a town or city) or some
other salient feature of the city.
How to interpret: