User's Guide
Data Variables and Sources
Information in this dataset is provided in an Excel spreadsheet,
consisting of four worksheets:
- Notes about coding conventions and data sources,
- Flags to identify States and years in which program benefit
data have been imputed by ERS (described below),
- State for State-level data, and
- County for county-level data. In general, the same variables
are available on both the State- and county-level files.
This dataset draws from a number of different sources and
represents estimates of true underlying values. Data for subsequent
years will be added to the dataset as updates are provided by the
Census Bureau and the Bureau of Economic Analysis.
Identifiers
- STATE_CD: Two-digit U.S. Postal Service code
identifying State.
- STFIPS: Two-digit Federal Information
Processing Standards (FIPS) code identifying State.
County-level file only:
- FIPS: Federal Information Processing
Standards code.
- FIPSTXT: FIPS code in text format with leading
zeros.
- COFIPS: County code portion of total FIPS code
(last three digits), not unique across States.
- CODEF: Source of county definition: BEA_ONLY
for Bureau of Economic Analysis, CEN_ONLY for Census Bureau, and
CEN_BEA for both Census Bureau and BEA using same definition.
- CONAME: County name and two-digit State
identifier.
- URBCODE: 2003 Rural-Urban Continuum Code per
ERS. For more information about the rural-urban code, see 2003
Rural-Urban Continuum Codes.
- METRO: Metro/nonmetro code per U. S. Census
Bureau. For the metropolitan/non-metropolitan codes used in the
data set, see Rural Definitions: Data
Documentation and Methods.
SNAP participant counts
Participation counts at the county level are provided by the
Small Area Income & Poverty Estimates program of the U.S.
Census Bureau. According to the Census
Bureau's website, the Census Bureau obtains raw data from the
Food and Nutrition Service (FNS), USDA. For most States, the
Census Bureau uses counts of participants for the month of July,
although some States can provide data only for other reference
periods.
For State-level figures, the Census Bureau calculates the number
of participants as a 12-month average running from July to June.
Since FY 2007, State-level participation counts have been based on
administrative records maintained by the Food and Nutrition Service
(FNS). Thus, the sum of participation counts for all counties in a
State (from FNS) may not equal the State total (from Census Bureau)
due to different data sources and definitions. FNS data for
participant counts are more accurate than estimates from the Census
Bureau, but FNS data are not uniformly available at the county
level.
- PRGNUMxx: Estimated number of active SNAP/Food
Stamp Program (FSP) program participants. The last two digits (xx)
indicate the year for the data. Data are available for 1989, 1993,
1995, and every year from 1997 through 2011 for States and through
2009 for counties. Some county-level data from FNS are available
for more recent fiscal years.
These data for earlier years are provided by the Small Area Income
& Poverty Estimates (SAIPE) section of the U.S. Census Bureau.
The original data come from the Food and Nutrition Service (FNS),
USDA.
For the county-level file, participant counts are usually for the
month of July. The Census Bureau controls the county-level values
to the State-level value. When the original data cover an area
larger than a single county, the Census Bureau uses a measure of
poverty in the multiple areas to apportion the SNAP/FSP caseload
numbers across the multiple areas.
State-level data through 2006 represent a 12-month average, with a
6-month delay. For instance, the values presented for 1995 are
based on the monthly average between July 1995 and June 1996. Since
2007, the data are based on the federal fiscal year; for example,
the values for 2008 are based on the monthly average between
October 2007 and September 2008.
Data fields for years prior to the introduction of the Food Stamp
Program in a particular county or State are coded as "-9995." If
the county's number of FSP participants was fewer than 50, the
field is coded as "-9998." See "Coding Conventions" below for more
details.
- PRGxx_yy: Percentage change in the number of
SNAP/FSP participants between the two years represented by "xx" and
"yy" in the variable name. Three of the six variables that are
included--PRG89-93, PRG93-00, and
PRG00-09--correspond to periods of major caseload
increases and declines. The variable PRG08-09 represents
the most recent annual comparison of average monthly participant
counts available in the dataset.
Users may construct their own change variables using estimates for
any combination of years. However, data are missing or not valid
for some counties in some years, and the convention is to code any
derived variable based on a variable with missing or invalid data
as "-9993". See "Coding Conventions" below for more details.
SNAP participant benefits
Estimates of total annual benefits issued by area are provided
by the Regional Economic Information System, Bureau of Economic Analysis of the U.S.
Department of Commerce. State and county estimates are based on
county tabulations of the distributed benefits from FNS,
USDA.
Benefit amounts are expressed in nominal dollars. There is no
adjustment for inflation.
- PRGBENxx: Estimated total annual amount of
SNAP/FSP benefits (in thousands) issued to State or county
residents in a year. The last two digits indicate the calendar year
for the data. Data are available for every calendar year from 1969
through 2009.
To obtain an estimate of average total benefits issued to all
State or county residents during a month, multiply the data value
by 1,000 and divide by 12.
These data are provided by the Regional Economic Accounts
Directorate of the Bureau of Economic Analysis (BEA) of the U.S.
Department of Commerce. The data measure the value of program
benefits issued to qualifying low-income households to supplement
their ability to purchase food. The State estimates are based on
USDA's tabulations of the value of distributed benefits. County
estimates are either based on payment data from the various State
departments of social services or imputed.
When county data for a given year are not available, BEA imputes
the county figures by applying the statewide percentage
change in benefits that year to each county's benefit data from the
prior year. States and years for which benefit data were imputed by
BEA are identified by the variables BENFLGxx(see below).
The BEA imputations are subject to large errors because the
procedure does not take into account different patterns of caseload
growth (or decline) among counties within a State. ERS has used a
different procedure to impute these annual benefit values. The
procedure uses State-level data to compute an average benefit
amount per participant per month. A county's estimated number of
participants in a given year is then multiplied by the statewide
average benefit (and multiplied by 12) to provide an imputed value
of annual benefits issued to participants in that county. This
imputation procedure assumes that average monthly benefit levels do
not vary by county within a State, which is, of course, a
simplification. Nevertheless, ERS's imputed values should be more
useful than those provided by BEA for most research purposes. To
reconstruct the BEA imputed value for any affected county, multiply
the county's total benefits from the previous year by the statewide
percentage change in benefits over the two years. Because BEA
imputations often occur for several years in a row, the
reconstruction of BEA's imputed values should begin with the
earliest consecutive year for which benefits were imputed.
The ERS imputation procedure is also used to estimate benefit
levels in geographic areas for which participant counts are
available but benefits amounts are not (for example, counties
marked as CEN_ONLY) and to correct BEA benefit data that lead to
values of average monthly benefits per participant that clearly
exceed program rules.
All benefit data and related variables are presented in nominal
dollars and have not been adjusted for inflation.
In some States (notably Alaska, Hawaii, and Virginia), BEA data on
benefits are for different geographic units than Census Bureau data
on participant counts. To sum across county records to derive State
or national totals and to avoid double-counting, use the variable
CODEF to exclude either CEN_ONLY or BEA_ONLY records.
- BENFLGxx: A flag indicating that the
corresponding value of PRGBENxx--same year and location--was
originally imputed by BEA and has been imputed by ERS using a
different procedure. The variable equals 1 if the corresponding
value is imputed and 0 if not. Program benefit data have not been
checked for BEA imputations prior to 2001.
Population counts
Area estimates of population counts are obtained from the U.S.
Census Bureau's website which includes a description of the methods
used to create the estimates.
- POPxx: Estimated population count, with the
year for the data indicated by the last two digits of the variable
name. Data are provided for every year from 2000 through 2010. The
reference date for estimates is July 1.
Data are provided by the Population Estimates Program of the U.S.
Census Bureau. With each new release of July 1 estimates, the
Census Bureau revises estimates for years back to the last
decennial census. The updated estimates are available for
2010.
Poverty counts
Area estimates of the number of persons in households with total
income below 100 percent of the Federal poverty level (FPL) are
provided by the Small Area Income & Poverty Estimates
Program of the U.S. Census Bureau.
- NUMPOVxx: Estimated total number of poor
people, with the year for the data indicated by the last two digits
of the variable name. Data are provided for 1999, 2000, 2006, 2007,
and 2010.
Data are provided by the Small Area Income and Poverty Estimates
(SAIPE) program of the U.S. Census Bureau. Estimates are based on
models that combine survey data with population estimates and
administrative records.
Ratios
A number of variables in the file compare participant counts or
program benefits to an underlying population group.
- PRG_POPxx: The ratio of program participants
to area population, with the last two digits of the variable name
indicating the data year. Values are provided for 2000, 2006, 2007,
and 2010.
- PRG_POVxx: The ratio of program participants
to area count of poor persons, with the last two digits of the
variable name indicating the data year. Values are provided for
2000, 2006, and 2007.
Note that the value of this variable will be less than one to the
extent that poor people are ineligible for the program for reasons
other than income or that eligible persons elect not to participate
in the program. The value may exceed one because the program's
gross income limits are higher than 100 percent of the Federal
poverty level.
- AMB_POPxx: The ratio of total average monthly
program benefits issued to all participants in an area to that
area's total population count, with the last two digits of the
variable name indicating the data year. Values are provided for
2000 and 2006.
- AMB_POVxx: The ratio of total average monthly
program benefits issued to all participants in an area to that
area's count of poor persons, with the last two digits of the
variable name indicating the data year. Values are provided for
2000 and 2006.
- AMB_PARxx: The ratio of total average monthly
program benefits issued to all participants in an area to that
area's count of program participants, with the last two digits of
the variable name indicating the data year. This variable estimates
average monthly benefits per participant over the course of a year.
Values are provided for all years from 2000 through 2009.
Note: when benefit data have been imputed, the average
monthly benefit per participant will be the same for all counties
in the affected State.
Coding Conventions
Data values are not always available for every variable and
every county. The following codes have been assigned for missing
data in the original files, along with an explanation of the reason
for which each code is used:
-
-9991: Data not yet available.
-
Null: No data, as indicated in the mapping
application. This includes data missing for the following
reasons:
-
-
-9992: Data not available for a county unit
used by BEA (CODEF=BEA_ONLY).
-
-9993: Computed variable for which at least one
underlying data value is missing.
-
-9994: Data not available for a county unit
used by Census Bureau (CODEF=CEN_ONLY).
-
-9995: Data not defined for years prior to
introduction of the Food Stamp Program (rollout of the FSP began in
1969 and was not fully nationwide until 1976).
-
-9996: Data missing due to data suppression by
BEA or Census.
-
-9997: Data not available in specific year.
Coded as (N) in original data files from BEA or Census.
-
-9998: Actual value less than 50. Coded as (L)
in original data files from BEA or Census.
-
-9999: Data not available for reasons other
than those listed above, including division by a true zero in a
computed variable.
Recommended Citation
Economic Research Service (ERS), U.S. Department of Agriculture
(USDA). Supplemental Nutrition Assistance Program (SNAP) Data
System. http://www.ers.usda.gov/data-products/supplemental-nutrition-assistance-program-(snap)-data-system.aspx.