Appendix A. 
Census of Agriculture Methodology 
The purpose of a census is to enumerate all objects 
with a defined characteristic. For the census of 
agriculture, that goal is to account for “any place 
from which $1,000 or more of agricultural products 
were produced and sold, or normally would have 
been sold, during the census year.” To do this, NASS 
creates a Census Mail List (CML) of agricultural 
operations that potentially meet the farm definition, 
collects agricultural information from those 
operations, reviews the data, corrects or completes 
the requested information, and combines the data to 
provide information on the characteristics of farm 
operations and farm operators at the national. State, 
and county levels. In this appendix, these census 
processes are described. 
THE CENSUS POPULATION 
The Census Mail List 
The National Agricultural Statistics Service (NASS) 
maintains a list of farmers and ranchers from which 
the Census Mail List (CML) is compiled. The goal is 
to build as complete a list as possible of agricultural 
places that meet the farm definition. The CML 
compilation begins with the list used to define 
sampling populations for NASS surveys conducted 
for the agricultural estimates program. Each record 
on the list includes name, address, and telephone 
number plus additional information that is used to 
efficiently administer the census of agriculture and 
agricultural estimates programs. 
NASS builds and improves the list on an ongoing 
basis by obtaining outside source lists. Sources 
include State and federal government lists, producer 
association lists, seed grower lists, pesticide 
applicator lists, veterinarian lists, marketing 
association lists, and a variety of other agriculture- 
related lists. NASS also obtains special commodity 
lists to address specific list deficiencies. These 
outside source lists are matched to the NASS list 
2012 Census of Agriculture 
USDA, National Agricultural Statistics Service 
using record linkage programs. Most names on 
newly acquired lists are already on the NASS list. 
Records not on the NASS list are treated as potential 
farms until NASS can confirm their existence as a 
qualifying farm. Staff in NASS field offices 
routinely contact these potential farms to determine 
whether they meet the farm definition. For the 2012 
Census of Agriculture, NASS made a concerted 
effort to work with Community-Based Organizations 
not only to improve list coverage for minorities but 
also to increase census awareness and participation. 
List building activities for developing the 2012 CML 
started in 2009 by updating list information from 
respondents to the 2007 Census of Agriculture. 
Between 2010 and 2012, NASS conducted a series 
of National Agricultural Classification Surveys 
(NACS) on approximately 1.7 million records, 
which included nonrespondents from the 2007 
census and newly added records from outside list 
sources. The NACS report forms collected 
information that was used to determine whether an 
operation met the farm definition. If the definition 
was met, the operation was added to the NASS list 
and subsequently to the CML. Addressees that were 
nonrespondents to a NACS were also added to the 
CML and identified with a special status code. 
Measures were taken to improve name and address 
quality. Additional record linkage programs were 
run to detect and remove duplicate records both 
within each State and across States. List addresses 
were processed through the United States Postal 
Service’s National Change of Address Registry and 
the Locatable Address Conversion System to ensure 
they were correct and complete. Records on the list 
with missing or invalid phone numbers were 
matched against a nationally available telephone 
database to obtain as many phone numbers as 
possible. To reduce costs, operations with 
characteristics that indicated they were unlikely to be 
farms, according to the farm definition, were 
APPENDIX A A- 1 
