Source: U.S. Bureau of Labor Statistics  

Release: Metropolitan Area Employment and Unemployment  

Units:  Persons, Not Seasonally Adjusted

Frequency:  Annual

The United States Office of Management and Budget (OMB) delineates metropolitan and micropolitan statistical areas according to published standards that are applied to Census Bureau data. The boundaries of statistical areas are periodically revised and are subject to change. For additional information, see here (https://www.census.gov/programs-surveys/metro-micro.html)