County Business Patterns provides data on the total number of establishments, mid-March employment, first quarter and annual payroll, and number of establishments by nine employment-size classes by detailed industry for all counties in the United States and the District of Columbia . 

Employers without a fixed location within a state (or of unknown county location) are included under a "statewide" classification at the end of the county tables. This incomplete detail causes only slight understatement of county employment. The independent cities in Virginia, and the cities of Baltimore, MD; Carson City, NV; and St. Louis, MO, are treated as separate counties.

ZIP Code Business Patterns presents data on the total number of establishments, employment and payroll for more than 40,000 ZIP Code areas nationwide. In addition, the number of establishments for nine employment-size categories is provided by detailed industry for each ZIP Code. 

Most ZIP Codes are derived from the physical location address reported in Census Bureau programs. The Internal Revenue Service provides supplemental address information. Those employers without a fixed location or with an unknown ZIP Code are included under an "Unclassified" category indicated by ZIP Code 99999.