The primary factor in the determination and assignment of counties to BSAs is commuting patterns among the counties. BSAs will therefore include both the place of work and the place of residence of the work force. The result is that BSAs are geography where travel and employment variables are in approximate equilibrium. Each BSA is designed to be as small as possible, while maintaining this relationship with its geography. These properties are essential to creating BSAs.
Small size is important in a very practical way.
For maximum control, businesses tend to require the smallest areas for sales and marketing analysis as well as for plant locations. BSAs use a single economic node or center county combined with the surrounding counties, selected using economic factors. Most of these center counties or nodes are contained in metropolitan areas while 100f these center counties are non-metropolitan. In the non-metropolitan areas, BSAs have common newspaper readerships and other widely read media. These non-metropolitan BSAs are treated identically with the BSAs that are based upon Metropolitan Area analysis.