National Center for Farmworker Health
Call for Health
1770 FM 967 • Buda, TX 78610
(512) 312-2700
(800) 531-5120
fax (512) 312-2600
March 2015
Feb Apr

Enumeration and Population Estimates

 Estimating the number of farmworkers on a national basis or even for a specific geographic area has been challenging for numerous reasons including the mobile nature of the population, the seasonal nature of agricultural work, the varying agriculture tasks performed and the fact that there is no local, state or national agency responsible for collecting this information. Numerous attempts have been made over the years to estimate the population and many formulas have been developed and used, each with its own strengths, weaknesses and shortcomings. NCFH has worked with many of the individuals attempting to resolve this riddle and answer the million dollar question, "How many farmworkers are there in the United States?", and offers the following resources for review and consideration.

Farmworker Population Estimation Services
NCFH has developed a conservative and defensible population estimation methodology using the best available data and a readily understandable formula to compute farmworker population estimates. The database was developed in collaboration with the contractual services of JBS International, Inc., Aguirre Division, and funded by the Health Resources and Services Administration, USDHHS.  Data rendered from this methodology is available at two levels:

Level 1:

Threshold Estimates Data at this level is derived from the United States Department of Agriculture’s (USDA) 2007 Census of Agriculture [1] which reports the number of agricultural employees and the dollars paid to contract workers, adjusted to estimate the total number of employees and contractual total workers.  The Department of Labor’s (DOL) National Agricultural Worker Survey (NAWS) [2] data provides a regional factor that is used to estimate the number of non working dependents, including both children and spouses, which is used to derive the threshold estimate of the minimum number of workers and dependents in the area. Data is not verified through oral intelligence.

Level 2:

Comprehensive Local Estimates:  Additional research can be conducted on a fee for service basis to verify the threshold data. Twelve sources of data from four federal agencies are used in this methodology, including:  United States Departments of Agriculture, Labor, Education, and Health and Human Services.   The methodology that we have adopted puts the population estimates into context by providing a rich, textured portrait of farmworkers and agricultural activity at the local level.  It is flexible enough to allow for adjustment of the estimates based on local intelligence of factors that affect the farmworker population that are not reflected in the data.  The following is a list of what NCFH will provide in the population estimation report.


A.     Agricultural Profile of the Selected Area

  • Number of farms & acres used for farming
  • Average farm size
  • The principal crops grown and harvested
  • Seasonal employment data that provides a general overview of agricultural employment  trends including peak periods for employment of farmworkers


B.    Population Estimates

  • The number of farmworkers, as reported by the 2007 Census of Agriculture.  This includes the numbers of:

                1.      Migrant Farmworkers

                2.      Seasonal Farmworkers

  • Percentage and number of  farmworker dependents, based on data from the       National Agricultural Workers Survey.  This includes the number of:

               1.      Children (minors) of Farmworkers

               2.      Spouses of Farmworkers not already counted as agricultural workers

  • Adjustment of estimated population to include aged and disabled farmworkers using a rational formula based on US Census information for the local area.
  • NCFH will conduct extensive interviews with local and state experts in order to validate and make adjustments and correct for any variations that may have occurred     since the prior Census of Agriculture and for local factors.  This includes input from service area experts on:    Turnover, underemployment, seasonal climate events affecting work force, workers residing in counties, but working in other counties, aged and disabled former farmworkers and their dependents, and others as unique to each area

C.   GIS Mapping

  • NCFH will provide maps of your county and/or state that visually represent all of the data discussed above.  The maps can be adjusted to fit the needs of the client. 
  • The number of farmworkers in a selected area along with the locations of community and migrant health centers to help indentify gaps in health service areas.
  • The locations of community and migrant health centers including satellite centers along with the locations of agricultural businesses within a selected area to help clients focus outreach efforts.


D.   Identification of Agricultural Employers

  • Addresses and contact information of agricultural businesses in the selected area.

NCFH will provide technical assistance to individuals and organizations interested in estimating their local farmworker population.

If you have any questions or concerns, please do not hesitate to contact Bethany Boggess at 512-312-2700 ext. 5455  or at


Available Estimation of Migrant and Seasonal Populations in Key States

Farmworker populations in 11 states were estimated in early 2000/01 using a standardized methodology developed by Dr. Alice Larson. The 11 states documented include Arkansas, California, Florida, Louisiana, Maryland, Mississippi, North Carolina, Oklahoma, Oregon, Texas, and Washington.  Oregon was completed in 2002 and 2013. Michigan was completed in 2006 and 2013. Idaho was completed in 2006 and Georgia and Arizona in 2008.

GIS Mapping of Enumerated States

In an effort to support the growth of migrant health centers through establishment of new access points and expansion of services, NCFH has produced a Geographic Information Services (GIS) Mapping presentation for each of the first 11 states based on Dr. Larson's findings (excluding Oregon, Idaho, Michigan, Georgia and Arizona). These eleven presentations portray a special analysis of the Larson Enumeration Study on a county by county basis in relation to existing community and migrant health center sites. The purpose is twofold: 1) To identify counties with no federally funded migrant health center sites where New Access Points might be appropriate, and 2) To graphically depict the highest concentrations of farmworker populations where existing Migrant Health Centers can expand their services in order to serve more farmworker patients.

Access to the GIS Analysis of the 11 states is available free of charge through this link NCFH GIS Mapping. It is designed to be very self-explanatory; however NCFH staff is available to walk interested parties through the presentation via teleconference, upon request.

[1]United States Department of Agriculture, Census of Agriculture, 2007

[2] United States Department of Labor, National Agricultural Workers Survey, 2005