The 2006-2010 ACS 5-year Summary File is accessible from the American Community Survey home page. From the ACS home page, www.census.gov/acs, click on the Data and Documentation tab, select the option for Summary File, as shown below:



That will take you to the ACS Summary File page. Click on 2006-2010 ACS 5-Year Summary File to go to the ACS Summary file page.





This is a screenshot of the 2008-2010 ACS 3-year Summary File page; the one for the 2006-2010 ACS 5-year Summary File looks very similar. It is actually comprised of three folders that are explained the next chapter.

Detailed Tables for similar subject areas are grouped together in "sequences". A sequence number is an assigned number to a grouping of ACS tables, and it may change from year to year or product to product (1-, 3-, or 5- year data sets). The rules governing how many tables can be assigned the same sequence number depend on the following:

• There are no more than 256 columns per sequence, so the data can be read into a spreadsheet.
• Tables are grouped into sequences according to subject area, but they are not in numerical order (i.e., Table B00001 is not in sequence file 0001).
• Tables with race iterations are grouped in the same sequence.

It is critical to know the sequence number associated with a Detailed Table (Table ID) for two reasons. First, one needs it in order to access the correct estimates and margins of error files for the desired table. Second, the field start position for the estimates or margins of error of a certain Detailed Table depends on its sequence number.

The Sequence Number and Table Number Lookup file-- available as an Excel spreadsheet, text file, and SAS dataset-- lists Table IDs associated with each sequence number. This spreadsheet, formerly known as "merge_5_6", is available at www2.census.gov/acs2010_5yr/summaryfile/. (The file is named "Sequence_Number_and_Table_Number_Lookup" with the ".xls", ".txt", or ".sas7bdat" extension.)

To find the sequence number associated with the table B08406, for example, a user must open and look for that Table ID in the Sequence Number and Table Number Lookup file. Shown below is a screenshot of this file, for the 2010 ACS 1-year, opened to where the "tblid" is B08406. The next column in the file, "seq", shows that this Table ID is associated with the sequence number "0003". In order to access the estimate and margin of error file for Table B08406, a user will need to download the estimate and margin of error files labeled with the sequence number "0003".

There is a geography file that comes with the estimate and margin of error files. This file begins with a "g" and is an ASCII file using either a position based format or comma delimited format. A geography file exists for each state or state level equivalent.

Geography files are named using the following convention:



The geography files contain geographic information for an ACS tabulated area, including the name of the area. One variable on the file, called LOGRECNO, is the logical record number and is used to link the level of geography to the estimate and margin of error files. An example of how to use LOGRECNO is discusses in Chapter 2.5.

The following table provides the layout of the geography file:

Variable Name	Description	Field Size	Starting Position	Geographic Summary Levels For 3-Year Tables
RECORD CODES
FILEID	Always equal to ACS Summary File identification	6	1	All Summary Levels
STUSAB	State Postal Abbreviation	2	7	All Summary Levels
SUMLEVEL	Summary Level	3	9	All Summary Levels
COMPONENT	Geographic Component	2	12	All Summary Levels
LOGRECNO	Logical Record Number	7	14	All Summary Levels
GEOGRAPHIC AREA CODES
US	US	1	21	10
REGION	Census Region	1	22	20
DIVISION	Census Division	1	23	30
STATECE	State (Census Code)	2	24	Reserved for future use
STATE	State (FIPS Code)	2	26	040, 050, 060, 160, 230, 312, 352, 500, 795, 950, 960, 970
COUNTY	County of current residence	3	28	050, 060
COUSUB	County Subdivision (FIPS)	5	31	60
PLACE	Place (FIPS Code)	5	36	160, 312, 352
TRACT	Census Tract	6	41	Reserved for future use
BLKGRP	Block Group	1	47	Reserved for future use
CONCIT	Consolidated City	5	48	Reserved for future use
AIANHH	American Indian Area/Alaska Native Area/ Hawaiian Home Land (Census)	4	53	250
AIANHHFP	American Indian Area/Alaska Native Area/ Hawaiian Home Land (FIPS)	5	57	Reserved for future use
AIHHTLI	American Indian Trust Land/ Hawaiian Home Land Indicator	1	62	Reserved for future use
AITSCE	American Indian Tribal Subdivision (Census)	3	63	Reserved for future use
AITS	American Indian Tribal Subdivision (FIPS)	5	66	Reserved for future use
ANRC	Alaska Native Regional Corporation (FIPS)	5	71	230
CBSA	Metropolitan and Micropolitan Statistical Area	5	76	310, 312, 314
CSA	Combined Statistical Area	3	81	330
METDIV	Metropolitan Statistical Area- Metropolitan Division	5	84	314
MACC	Metropolitan Area Central City	1	89	Reserved for future use
MEMI	Metropolitan/Micropolitan Indicator Flag	1	90	010, 020, 030, 040, 314
NECTA	New England City and Town Area	5	91	335, 350, 352
CNECTA	New England City and Town Combined Statistical Area	3	96	335
NECTADIV	New England City and Town Area Division	5	99	355
UA	Urban Area	5	104	400
BLANK		5	109	Reserved for future use
CDCURR	Current Congressional District ***	2	114	500
SLDU	State Legislative District Upper	3	116	Reserved for future use
SLDL	State Legislative District Lower	3	119	Reserved for future use
BLANK		6	122	Reserved for future use
BLANK		3	128	Reserved for future use
BLANK		5	131	Reserved for future use
SUBMCD	Subminor Civil Division (FIPS)	5	136	Reserved for future use
SDELM	State-School District (Elementary)	5	141	950
SDSEC	State-School District (Secondary)	5	146	960
SDUNI	State-School District (Unified)	5	151	970
UR	Urban/Rural	1	156	010, 020, 030, 040
PCI	Principal City Indicator	1	157	010, 020, 030, 040, 312, 352
BLANK		6	158	Reserved for future use
BLANK		5	164	Reserved for future use
PUMA5	Public Use Microdata Area - 5% File	5	169	795
BLANK		5	174	Reserved for future use
GEOID	Geographic Identifier	40	179	All Summary Levels
NAME	Area Name	200	219	All Summary Levels
BTTR	Tribal Tract	6	419	256, 258, 291, 292, 293, 294
BTBG	Tribal Block Group	1	425	258, 293, 294
BLANK		50	426	Reserved for future use

This year, we created an Excel template for the geography file named "2010_SFGeoFileTemplate.xls". The template provides users with two rows containing the variable names and their descriptions (as displayed in the above table) for each column in the geography file. It is meant to be used with the comma delimited version of the geography file. The template is available at www2.census.gov/acs2010_5yr/summaryfile/UserTools/ in the zipped "2010_SummaryFileTemplates" zip file. Here is a screenshot of the Excel file:



Each state, the District of Columbia, Puerto Rico and the set of cross-state geographies, have one geography file associated with them regardless of how the Summary File is accessed. For example, the following screenshot shows the beginning of the state geography file for Maryland in the 2009 1-year ACS. In the screenshot, the logical record numbers corresponding with the state of Maryland, Allegany County, and Anne Arundel County are circled. The logical record number for the state of Maryland is "0000001", for Allegany County it is "0000012", and for Anne Arundel County it is "0000013".



Excess spaces in the pictured geography file have been removed for illustrative purposes.

Each of the three Summary File directories include zipped files containing estimate files (file names beginning with an "e") and margins of error files (file names beginning with an "m"). The estimate files contain published ACS estimates and the margin of error files contain published ACS margins of error for their respective estimates. Here is the naming convention used for those files:



The estimates and margins of error for Detailed Tables are grouped together in by sequence numbers, as discussed in Chapter 2.3. There is an estimate and margin of error file for each sequence number.

The format of the estimate and margin of error files are identical; they are strings of comma- delimited ASCII text. Each row represents a different geographic area and the first six fields contain metadata such as the geographic area and the sequence number. Following those fieldsare the estimates or margins of error for the Detailed Tables. Starting and ending positions of the fields associated with each Detailed Table can be found using the Sequence Number and Table Number Lookup file, which is discussed in Chapter 2.3. The estimates or margins of error for one Detailed Table span several fields within a row.

Here is the record layout of the estimates and the margin of error files:

Field Name	Description	Field Size
FILEID	File Identification	6 Characters
FILETYPE	File Type	6 Characters
STUSAB	State/U. S. - Abbreviation (USPS)	2 Characters
CHARITER	Character Iteration	3 Characters
SEQUENCE	Sequence Number	4 Characters
LOGRECNO	Logical Record Number	7 Characters
Field # 7 and up	Estimates	Various

Going back to the example from Chapter 2.3, we know that table B08406 corresponds to sequence "0003". Additionally, the Sequence Number and Table Number Lookup file (as shown earlier) tells us that table B08406 begins at position seven and contains 51 cells.

In order to get estimates for Maryland; Allegany County, MD; and Anne Arundel County, MD one must recall the logical record numbers associated with each geography. In Chapter 2.4, we identified these to be "0000001", "0000012", and "0000013", respectively. The logical record number, LOGRECNO, must be used to merge the geography information to the estimate and margin of error files.

The example below shows the estimate file for sequence "0003" and all geographies except census tracts and block groups for the state of Maryland using the 2010 ACS 1-year Summary File. Note that each row has a uniquely assigned logical record number, called LOGRECNO, which links the estimate to a specific geographic area. The pictured example has the logical record numbers corresponding to Maryland, Allegany County, and Anne Arundel County circled. Estimates for table B08406 at these geographic levels can be found within their respective rows at field seven and continuing for 50 additional fields.

TIGER/Line Shapefiles allow data users to directly link geographic areas to data from the American Community Survey and other surveys. The TIGER/Line Shapefiles are designed for use with geographic information system (GIS) software. Learn more about TIGER/Line Shapefiles at www.census.gov/geo/www/tiger/.

The variable GEOID joins the ACS Summary File to the TIGER/Line Shapefiles. For the ACS Summary File, GEOID is located in column AW of the geography file. It is not found in the estimates or margins of error files. (As discussed in previous chapters, the variable LOGRECNO is needed to join together the parts that make up the Summary File: the geography, estimates, and margins of error files). GEOID's corresponding variable in the 2010 TIGER/Line Shapefiles is GEOID10.

We will walk through an example of joining these files using Kent County, Delaware. In the ACS Summary File, the GEOID is 05000US10001. In the TIGER/Line Shapefiles, the GEOID10 is 10001. (GEOID is a concatenation of all the codes associated with a given geographic area, such as the state FIPS code, county FIPS code, etc. The exact concatenation varies by geographic area. In this example, 10=state FIPS code and 001=county FIPS code.)

The ACS Summary File GEOID contains the necessary information to connect to the TIGER/Line Shapefiles, but it needs to be modified in order to exactly match up. Notice that GEOID, 05000US10001, contains the GEOID10 string, 10001. In order to create an exact match of GEOID and GEOID10, it is necessary to remove all of the characters before and including the letter "S" in the ACS Summary File. By removing these characters, the new GEOID in the ACS Summary File exactly matches the field GEOID10 in the TIGER/Line Shapefiles.

The following is an example of how to modify the ACS Summary File's GEOID in Excel 2007 so it can be joined with TIGER/Line Shapefiles:

1. Open the ACS Summary File comma delimited geography file in Excel. This example uses Delaware's geography file (g20101de.csv) available at www2.census.gov/acs2010_3yr/summaryfile/ with the column headers from the geography file template copied into Delaware's geography file. Learn more about the geography file template in Chapter 2.4.
2. Insert 2 blank columns to the right of the column "GEOID." Your modified GEOID will eventually go into the second column. (Note: Columns F through AV in the diagrams following are hidden for illustrative purposes.)
   
   
   
3. Next, select the column "GEOID."
   
   
   
4. Select the "Data" tab from the top menu, then select "Text to Columns." to Columns Wizard" box should pop up.
   
   
5. In the "Convert Text to Columns Wizard," select "Delimited" under "Choose the file type that best describes your data:" then click "Next."
   
   
6. Check "Other" as the delimiter and type the letter "S" into the box. Click "Next.
   
   
7. In the "Data preview" window, click on the top of both columns in "Data preview" and select "Text" under "Column data format." In "Destination," select the two blank columns that you created in Step 1. Click "Finish."
   
   
   
8. Column AY should now contain the modified GEOID that corresponds to GEOID10 in the TIGER/Line Shapefiles. The second screenshot shows the TIGER/Line Shapefile for Kent County, Delaware.
   
   
9. The ACS Summary File and the TIGER/Line Shapefile should now be ready to be joined using GIS software. Visit "Working with TIGER/Line Shapefiles" at http://www.census.gov/geo/www/tiger/wwtl/wwtl.html to learn more about how to access and use the TIGER/Line Shapefiles.