2009 ACS 1-Year Summary File: Technical DocumentationAmerican Community Survey OfficeU.S. Census BureauDate:Version: 1.0September 27, 2010Document HistoryVersion Number1.0American Community Survey Summary FileDateSeptember 27, 2010Summary of ChangesBaseline DocumentPage 1 of 34


Chapter 1 - AbstractINTRODUCTIONThe American Community Survey (ACS) is a relatively new survey conducted by theU.S. Census Bureau. It uses a series of monthly samples to produce annually updateddata for the same small areas (census tracts and block groups) formerly surveyed via theDecennial Census long-form sample. Five years of data collection will be required toproduce these small-area data. Once the Census Bureau has collected 5 years of data,new small-area data will be produced annually. The Census Bureau will produce 3-yearand 1-year data products for larger geographic areas. The ACS includes people living inboth housing units (HUs) and group quarters (GQs). The ACS is conducted throughoutthe United States and in Puerto Rico, where it is called the Puerto Rico CommunitySurvey (PRCS). For ease of discussion, the term ACS is used here to represent bothsurveys.The American Community Survey releases meaningful data products on the CensusBureau‘s American FactFinder website. To address other requests, the AmericanCommunity Survey produces the Summary File product that contains the complete set ofthe detailed tables in a comma delimited file format to allow for importation of this datainto databases, spreadsheets, SAS datasets, and other formats. The AmericanCommunity Survey‘s Summary File follows the approach taken for the Census 2000Summary File 3 format. The American Community Survey Summary File consists ofapproximately 1,300 detailed tables of demographic, social, economic, and housingcharacteristics for the 1-year and 3-year products. For information about Censusgeographies, please visit .The American Community Survey detailed tables contain both a base and collapsedversion. The base tables provide detailed information on a given topic, and the collapsedtables provide a consolidated version of a base table. The base table name begins withthe letter ―B‖ and the collapsed table name begins with the letter ―C‖ to allow for easyidentification.The American Community Survey covers a broad spectrum of geographic areas withinthe United States and Puerto Rico. The American Community Survey dividescharacteristics into demographic, social, housing, and economic topics.Demographic:o Sexo Households by typeo RelationshipAmerican Community Survey Summary Fileo Ageo Raceo Hispanic originPage 3 of 34

Social:oooooooSchool enrollmentFertilityVeteran statusU.S. citizenship statusMarital statusYear of entryGrandparents caring for childrenoooooooEducational attainmentResidence one year agoDisability statusLanguage spoken at homePlace of birthAncestryWorld region of birth of foreign bornooooCommuting to workIncome and benefitsOccupationHealth Insurance CoverageoooooooHousing tenureYear structure builtNumber of bedroomsHousing valueVehicles availableUtility costGross rentEconomic:ooooEmployment statusClass of workerIndustryPoverty statusHousing:oooooooHousing occupancyUnits in structureNumber of roomsHouse heating fuelOccupants per roomMortgage status and costsYear householder moved into unitGEOGRAPHIC CONTENTThe American Community Survey Summary Files include all detailed tables for allgeographic areas published by the 2009 1-Year ACS. The main directory of theAmerican Community Survey‘s Summary File product release, located within the filetransfer protocol (FTP) site, contains documentation about the Summary Files andinformation pertaining to the United States, each of the individual states, the District ofColumbia, and Puerto Rico.The following list outlines the hierarchical geographic levels contained within theSummary File release.State FilesThe ACS 1-Year Summary File for states contains the following geographic areas:o Stateo CountyAmerican Community Survey Summary FilePage 4 of 34

ooooooooCounty SubdivisionPlaceMetropolitan Statistical Area/Micropolitan Statistical Area-State-Principal CityNew England City and Town Area-State-Principal CityState-School District (Elementary, Secondary, and Unified)State-Alaska Native Regional CorporationCongressional District (111th Congress)Public Use Microdata Sample Area (PUMA)National FilesThe ACS Summary File for the U.S. contains the following geographic areas:oooooooooooUnited StatesRegionDivisionAmerican Indian Area/Alaska Native Area/Hawaiian Home LandMetropolitan Statistical Area/Micropolitan Statistical AreaMetropolitan Statistical Area-Metropolitan DivisionCombined Statistical AreaCombined New England City and Town AreaNew England City and Town Area (NECTA)-NECTA DivisionNew England City and Town AreaUrban AreaCONTACT USPlease send any technical questions or comments you have via email to:[email protected] If you have questions or comments about the AmericanCommunity Survey, please contact us online at Community Survey Summary FilePage 5 of 34

Chapter 2 – How to Use the ACS Summary FileINTRODUCTIONThis chapter is intended to provide a guide for data users to the American CommunitySurvey Summary Files. New users should review this chapter before attempting to usethe Summary File product.DATA FORMATThe American Community Survey Summary Files (ACS-SF) are available in .zip fileformat. The Zip file format is a compressed format used to reduce the file size. Userscan download the .zip files through the File Transfer Protocol (FTP) from the AmericanCommunity Survey FTP site located at 1yr/summaryfile/. To read the Summary Files data, thecompressed files must be uncompressed (unzipped) to allow access to the data.NEW ORGANIZATION OF ACS SUMMARY FILESBased on user feedback, the ACS Summary File is now organized into three categories1. Entire SF: This zip file contains all of the Summary File data, MOE's, andgeography files - 1 File in Directory/acs2009 1yr/summaryfile/Entire SF/20091YRSF.zipFor the user‘s convenience, this zip file contains all of the Summary Files for the U.S.,Puerto Rico, states, and District of Columbia. For example, to obtain all Summary Filesfor nation (U.S.), states, District of Columbia, and Puerto Rico, just download and unzipthe file Community Survey Summary FilePage 6 of 34

2. Entire States: These files contain all of the summary file data, MOE's, andgeography files per state - 53 Files in Directory (50 States, 1 US, DC, PR)/acs2009 1yr/summaryfile/Entire States/ FULL STATE NAME .zipThis directory contains 53 zip files that include the United States, each of the 50states, District of Columbia, and Puerto Rico. Each zip file contains 176 estimatefiles, 176 Margin of Error files, and 1 geography file. See partial contents of thezip file for Alabama below.3. Seq By ST: 53 directories with 176 Compressed Sequence Files (both Estimates& MOE's) and 1 Geography file in each directory/acs2009 1yr/summaryfile/Seq By ST/ ST ABBRV / Sequence ID .zipAmerican Community Survey Summary FilePage 7 of 34

Each directory contains 176 zip files and 1 geography file. Each zip filecontaining 1 estimate and 1 Margin of Error file. See a partial view of the AKdirectory below:American Community Survey Summary FilePage 8 of 34

FILE NAMING CONVENTIONSThe naming convention used for the Summary Files provides a hierarchy to allow foreasier navigation to the desired information. Figures 2.1 and 2.2 provide an overview ofthe summary file naming convention.Figure 2.1Zip File Naming Convention Examplet yyyypggssssiter.zipPlaceholder for futureiteration valuesType of fileGeographic areaReference year forthe dataFile sequence number(from 0001 9999)Period covered bythe filet type of data (e estimate, m margin of error)yyyy reference year for the data, e.g., 2009p period covered by the file (1 1-year, 3 3-year, 5 5-year)gg geographic area (state or US) covered by the file; ‗PR‘ for the Puerto RicoCommunity Surveyssss file sequence number (valid range is 0001 through 9999)Each sequence number will correspond to a series of detailed tables. Each record of thisfile will be for a unique geographic area published by the ACS. All the data cellscontained in the detailed tables for that geographic area would be on this record. Therewill be a file for the estimates and a separate one for the margin of errors.American Community Survey Summary FilePage 9 of 34

iter ‘000’, placeholder for future values for iterationr data revision indicator, only present if needed. ‗a‘, ‗b‘, etcFigure 2.2Geoheader Summary File Naming Convention Exampletyyyypgg.txtType of filePeriod covered bythe fileGeographic areaReference year forthe datat type of data (g geographic header file)yyyy reference year for the data, e.g., 2009p period covered by the file (1 1-year, 3 3-year, 5 5-year)gg geographic area is represented by 2 digit FIPS state codeREADING THE GEOGRAPHIC FILEThe geographic file layout is below (Table 2.1). The geographic file provides thereference name, field description, field size, field starting position, and geographicsummary levels that apply. The information pertaining to summary level identifiesadditional geographic information. Each record of the geographic file contains particulargeographic area codes. For example, the reference name ―PLACE‖ only containsinformation for summary levels 160 - State-Place, 312 - Metropolitan StatisticalArea/Micropolitan Statistical Area-State-Principal City and 352 - New England City andTown Area-State-Principal City. For more detail on geographic definitions, see"Geographic Terms and Concepts"American Community Survey Summary FilePage 10 of 34

Table 2.1 Geographic Header Record Layout for the ACS Summary FileData DictionaryReference NameRECORD ICAREA ays equal to ACS Summary FileidentificationState Postal AbbreviationSummary LevelGeographic ComponentLogical Record Number61All Summary Levels2327791214All Summary LevelsAll Summary LevelsAll Summary LevelsAll Summary LevelsUSCensus RegionCensus DivisionState (Census Code)State (FIPS Code)111222122232426County of current residenceCounty Subdivision (FIPS)Place (FIPS Code)355283136615441474853010020030Blank for All Summary Levels040, 050, 060,160, 230, 312, 352, 500,795, 950, 960, 970, M01, M06, M07,M08, M11, M15, P01, P06, P07, P08,P11, P15050, 060, M01, M08, P01, P08060, M08, P08160, 312, 352, M07, M11, M15, P07,P11, P15Reserved for future useReserved for future useReserved for future use250557250135556263667176358184Reserved for future useReserved for future useReserved for future use230310, 312, 314, 332, M10, M11, M12,P10, P11, P12330, M09, P09314, M12, P12115899091396010, 020, 030, 040, 314350, 352, 355, M14, M15, M16, P14,P15, P16335, M13, P1355523399104109114116119355, M16, P16400Reserved for future use500Reserved for future useReserved for future useAmerican Indian Area/Alaska Native Area/Hawaiian Home Land (Census)American Indian Area/Alaska Native Area/Hawaiian Home Land (FIPS)Alaska Native Regional Corporation (FIPS)Metropolitan and Micropolitan StatisticalAreaCombined Statistical AreaMetropolitan Statistical Area-MetropolitanDivisionMetropolitan Area Central CityMetropolitan/Micropolitan Indicator FlagNew England City and Town AreaNew England City and Town CombinedStatistical AreaNew England City and Town Area DivisionUrban AreaCurrent Congressional District ***American Community Survey Summary FileGeographic Summary Levels ForSingle-Year TablesPage 11 of 34

KPUMA5BLANKGEOIDNAMEState-School District (Elementary)State-School District (Secondary)State-School District (Unified)Urban/RuralPrincipal City IndicatorPublic Use Microdata Area – 5% FileGeographic IdentifierArea NameAmerican Community Survey Summary 58164169174179219Reserved for future useReserved for future useReserved for future useReserved for future use950960970010, 020, 030, 040010, 020, 030, 040, 312, 352Reserved for future useReserved for future use795Reserved for future useAll Summary LevelsAll Summary LevelsPage 12 of 34

IDENTIFICATION FIELDS WITHIN SUMMARY FILEThe first six columns of the estimates and margin of error files provide data andgeographic information related to the tables contained within the same row.FILEID File Identification - 6 charactersFILETYPE File Type - 6 charactersSTUSAB State/U.S.-Abbreviation (USPS) - 2 charactersCHARITER Character Iteration - 3 charactersSEQUENCE Sequence Number - 4 charactersLOGRECNO Logical Record Number - 7 charactersA logical unique record number is assigned to all files for a specific geographic entity sothat all records for a specific entity can be linked together across files. Besides thelogical record number, other identifying fields are also carried over from the geographicheader file to the table files. For more details on these fields, see the example below.TABLE B08406:SEX OF WORKERS BY MEANS OF TRANSPORTATION TO WORK FOR WORKPLACE GEOGRAPHYFILEIDFILETYPESTUSABCHARITERSEQUENCE LOGRECNOTotalCar,Truck,or American Community Survey Summary FilePage 13 of 34

SEQUENCE RULES AND TABLE IDThere are a few simple rules that are followed in the organization of tables into sequencesin the ACS Summary File.There are never more than 245 cells in a sequence. Tables are grouped intosequences according to their subject area.Tables from different subject areas are not combined into the same sequence.Tables are grouped together when they share a collapsing arrangement. (Group B& C tables in same sequence.) For example, tables B02003 and C02003 should bein the same sequence. Place of Work (POW) tables are not grouped together withPlace of Residence (POR) tables.The data from the American Community Survey contain approximately 75 detailed tablesthat have different table layouts for the Puerto Rico Community Survey. The UnitedStates tables are limited to geographic areas within the United States that includes all 50states plus the District of Columbia. The Puerto Rico tables are limited to areas withinPuerto Rico. Separation of files between US and Puerto Rico was made because thecomparable tables may have a different number of cells (such as C06001 with 45 cellsand C06001PR with 37 cells). To identify what tables are available for Puerto Rico onlylook for the "PR" suffix in the table id (e.g. C06001PR). For more information on PRonly sequences that are counterparts to states-only sequences, please reference thefollowing table.US/State-onlySequences – MissingPR Data1 (US)2 (US)23 (US)24 (US)28 (US)29 (US)30 (US)31 (US)32 (US)165 (US)American Community Survey Summary FilePR OnlySequences –Missing US/StateData167 (PR)168 (PR)169(PR)170 (PR)171 (PR)172 (PR)173 (PR)174 (PR)175 (PR)176 (PR)Page 14 of 34

Sequences 126-143 contain 6 large median tables with 499 cells. Due to the sizerestriction on the sequences (no more than 245 cells), each of the tables is broken downinto 3 sequences. These tables are only produced for the U.S. Please reference thefollowing table for more details.US 38139140141142143American Community Survey Summary FileUS B24126B24126B24126Page 15 of 34

Chapter 3 – Table ShellsA file containing all of the table shells is available at the top level of the Summary Filedirectory along with the technical documentation, and it is called:ACS2009TableShells.xls. Here is an example of the contents of the file.TABLE SHELLSTableIDB00001B00001B00001LineUnique IDStubUNWEIGHTED SAMPLE COUNT OF THE POPULATIONUniverse: Total population1 B00001001 TotalB00002B00002UNWEIGHTED SAMPLE HOUSING UNITSUniverse: Housing unitsB000021 B00002001 To