A perennial farm worker question is: how many? The most common approach to answer the how-many question is a top-down approach, beginning with a comprehensive data source such as the Census of Agriculture and converting the farm labor expenditures reported by farmers into hours worked, and hence the number of workers. Farmers reported $33.5 billion in farm labor expenses in the 2012 COA, including 69 percent paid by crop farms.

Dividing labor expenses by the average hourly earnings of crop and livestock workers yields hours worked, which translates into both full-time equivalent jobs (2080 hours a year) and unique workers (with sample data on average hours worked), yielding 1.4 million Full-Time Equivalent (FTE) jobs and 2.1 million unique workers in 2012. About three-fourths of farm jobs and workers are in crops.

For California, this top-down method yields 488,000 farm workers in 2012, including 91 percent in crops. However, a count of unique SSNs reported by employers with agricultural NAICS codes yields more farm workers, over 800,000.