“Dates and style labels are used as general guidelines to distinguish various design forms. Care must be used in attaching design labels to specific buildings. Few examples of pure styles exist.
Before 1870, the major design resource for builders were “pattern“ books that illustrated plans and elevations of buildings. Often houses were built with parts from more than one pattern, and favorite details of several styles were combined. In addition, many styles received local variations in response to different climates, availability of building materials, and personal needs. In many cases, designs continued to be built in some areas of the country long after they were considered out of fashion in others.”