From the U.S. Census:
The U.S. Census Bureau today released the 2017 County Business Patterns (CBP).
This annual series of statistics provides subnational economic data by industry. These data show detailed annual information on the number of establishments, first quarter employment, and first quarter and annual payroll at the national, state, metropolitan area, county and congressional district levels for nearly 1,200 industries defined by the North American Industry Classification System (NAICS).
The data are useful for studying economic activity of small areas. Federal agencies use the data to determine employee concentrations and trends by industry. Private businesses use the data for analyzing market potential, measuring the effectiveness of sales and advertising programs, setting sales quotas, and developing budgets. State and local government offices use the data to assess business changes, develop fiscal policies, and plan future policies and programs.
CBP basic data items are from the Business Register (BR), a database of all known single- and multi-establishment employer companies maintained and updated by the Census Bureau.