From the U.S. Census:
2012 annual data for metropolitan statistical areas now available in spreadsheet and comma-delimited format and 2012 county annual data now available in spreadsheet format. Statistics include number of firms, establishments, employment, annual payroll, and estimated receipts.
2012 data will be released through December 2015.
Direct to Statistics for U.S. Businesses Data Files
See Also: Previous Statistics of U.S. Businesses Data Releases
See Also: Introduction to U.S. Businesses Data Statistics (via U.S. Census)