A quick overview of the business environment in your city, county or state can be found at QuickFacts from the US Census Bureau. How to search video
Current numbers for both the County Business Patterns and the Nonemployer Statistics are now part of the https://data.census.gov website. How-To Video (Silent)
Past data for the number of establishments with employees in each industry, broken down by employee size, may be found in County Business Patterns (organized by NAICS).
Past data for businesses without employees run by the self-employed are located at the Nonemployer Statistics for states, metro areas, and counties (also organized by NAICS).