A"Benchmark" is an annual revision process in which monthly labor force and payroll employment by industry estimates are updated.  Throughout the year, employment by industry data are estimated based on sample data.  On an annual basis, when updated information becomes available from detailed tax records, the employment by industry estimates are revised.  Tax record data are used through March; therefore, the revision is referred to as the March Benchmark.

The labor force data series is also revised.  The labor force statistics are calculated based on a number of data sources including the employment by industry data, Unemployment Insurance claims filed, and at the State level, data from the Current Population Survey (CPS), a survey of households.  As these industry employment and CPS data are updated, so are the labor force statistics.

Because this review and update process is so extensive, and affects historical as well as current year data, the information is released in stages early each year.  For more information on Benchmarking:  U.S. Bureau of Labor Statistics.