1. What is Geocoding?

1. What is Geocoding? Geocoding is an attempt to provide the geographic location (latitude, longitude) of an address by matching the address to an address range. The address ranges used in the geocoder are the same address ranges that can be found in the TIGER/Line Shapefiles which are derived from the Master Address File (MAF). The address ranges are potential address ranges, not actual address ranges. Potential ranges include the full range of possible structure numbers even though the actual structures might not exist. The majority of the address ranges we have are for residential areas. There are limited address ranges available in commercial areas. Our address ranges are regularly updated with the most current information we have available to us. The hypothetical graphic below may help customers understand the concept of geocoding and Census Geography (addresses displayed in this document are factitious and shown for example only.) If we look at Block 1001 in the example below the address range in red 101-199 is the range of numbers that overlap the actual individual house numbers associated with the blue circles (e.g. 103, 117, 135 and 151 Main St) on that side of the street (i.e. the Left side, note the arrow is pointing to the right on Main Street.) Based on this logic, the from address would be 101 and the to address would be 199 for this address range. Besides providing a user with the geographic location of an address the Census Geocoder can also provide all of the additional Census geographic information associated with a location, for example a Census Block, Tract, County, and State.

For a definition of many of the Census terms discussed in this document please consult the Census Bureau's Geography Reference page at ().

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2. How do I create a digital file so that I can submit my addresses for batch geocoding? An important first step to preparing your file for batch geocoding is to format your spreadsheet of addresses into 5 columns like the example below.

Note: City, State and Zip Code fields can be left blank. See example below.

The geocoder accepts input files in text (.csv, .txt, .dat) and Excel format (.xls, .xlsx). The output file is provided in the same format as the input file. Most database software products have the option of saving your file in these formats. 3. What is the Census Geocoder? The Census Geocoder () allows customers the ability to submit one or many addresses (10,000 addresses is the limit) to determine their geocode (interpolated latitude and longitude) if they fall within a census address range. The latitude and longitude coordinate system is NAD83. There are seven different geocoding options to choose from on the home page: there are three options under "Find Locations Using" and four options under "Find Geographies Using," see example below.

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We will discuss each of these below and group them based on the similarity of their output product. A. Find Locations Using... One Line. For this selection the user types in one address in the text box, using comma's to separate the different address components, note example below.

The user gets the option to choose three different address range (AR) benchmarks in the Benchmark pulldown menu.

Benchmark refers to the time period when the address range was captured in TIGER. Public_AR_Current is the most current benchmark. More Benchmark information is discussed in Section #4, What does Benchmark and Vintage Mean? A discussion of the output is provided in Appendix A. B. Find Locations Using... Address. These options allow the user to input an address through a series of text boxes to get a geocode (see example below.)

A discussion of the output is provided in Appendix A. 3

C. Find Locations Using ... Address Batch. This option allows the user to submit multiple addresses in a digital file formatted in text (.csv, .txt, .dat) or Excel (.xls, .xlsx).

To get started the user selects their digital address file for input with the browse button, next the user can choose a Benchmark type, and finally one clicks the Get Results button to receive the output information. After the processing is complete the user will be prompted by their web application if they would like to open the GeocodResults.csv file or save it, note screen shot below.

The output information in shown in Appendix B. D. Find Geographies Using ...

There are four options using the Find Geographies Using ... method which is discussed below. I. Find Geographies Using ... One Line. For this option the user types in one address in the text box, using comma's to separate the different address components (see example below.)

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This option allows the user to choose a different address range (AR) benchmark (discussed above) and different Geography Vintage types (note image below.)

Vintage is the date when the geography information was captured. More Vintage information is discussed in Section #4, What does Benchmark and Vintage Mean? The output information is shown in Appendix C. II. Find Geographies Using ... Address This option allows the user to input an address through a series of text boxes, see example below.

Again the user has the option of choosing a different Benchmark and Vintage. The output information in shown in Appendix C. III. Find Geographies Using ... Address Batch.

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This option allows the user to submit multiple addresses in a digital file formatted in text (.csv, .txt, .dat) or Excel (.xls, .xlsx) to obtain the Census Geography information associated with the address.

To get started the user selects their digital address file for input with the browse button, next the user can choose a Benchmark and Vintage type, and finally the user clicks the Get Results button to receive the output information. After the processing is complete the user will be prompted by their web application if they would like to open the GeocodResults.csv file or save it, note screen shot below.

The output information in shown in Appendix D. IV. Find Geographies Using ... Geographic Coordinates.

This option allows the user to submit Longitude (X) and Latitude (Y) coordinate values to determine the geography associated with that location.

The output information in shown in Appendix C. Note that this option does not output any address range information. 4. What does Vintage and Benchmark mean? Benchmark refers to the date or time frame when the address range repository was last updated. Vintage refers to the date or time frame when the geography is from. If you choose an address range from an earlier time frame you will only be able to choose geography from

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that time or earlier. So for example if you choose a 2010 Benchmark Address Range you will only have the option of choosing Vintage geography from either 2000 or 2010. If you choose a current Benchmark Address Range you will have the option of choosing Vintage geography from Current, ACS2015, ACS2014, ACS2013 or Census 2010.

5. Possible reasons your address did not geocode. There are several possible reasons why an address you submit may not geocode to a Census address range. The Street and address that you submitted truly does not exist or has not been built. The address is a newly constructed home that has not yet been captured by our address capturing techniques. The address may have existed at one time but now does not exist (i.e. the housing unit may have been demolished or destroyed by natural or man-made causes.) The address may have existed at one time but now does not exist (i.e. the housing unit address may have been changed to a non-residential one.) The house number or street name may have changed because of renaming and/or renumbering due to E911 activities. The address submitted matches to a single address range street segment. Because of the Census Bureau's commitment to Title 13 individual address information is considered confidential information and thus cannot be released to the public. A single address range street segment essentially identifies the location and name of a single address which is prohibited and cannot be released.

Our address ranges consist mainly of residential addresses. If you do not get a result and you know the approximate location of the address, we recommend you use our TIGERweb interactive map viewer. If you do not know the approximate location we recommend you use outside sources to determine the approximate location. We are continually improving our addresses and address ranges. We release updated geography and address ranges at least once per year. Please send any questions or comments to geo.geocoding.services@.

6. LUCA participants

Entities submitting address lists for geocoding to the LUCA Geocoder will submit their addresses to the Census Bureau via the SWIM application. The address list file submitted to the LUCA geocoder can exceed 10,000 records and must be in a .csv format similar to the formats discussed above for the public geocoder. All files submitted to the LUCA geocoding must be formatted into 5 columns like the example shown in Section 2 above.

The output products that are returned to the LUCA participants are provided to assist them with their LUCA submission. We shall discuss these specific data products next.

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Output file format for the Address Count List.

Address Geocoding Output File Layout for the Address Count List

Column Name MATCHED = `M'

MATCHED = `T' MATCHED = `U' TABSTATE TABCOUNTY TABTRACT TABBLOCK

ADDRESS COUNT

Example The total number of addresses that matched to an address range. The total number of addresses that tied between two or more Census address ranges. A Tie indicates multiple possible results for that address. The total number of addresses that did not match to an address range. Tabulation State FIPS Code Tabulation County FIPS Code Census Tabulation Tract Code Census Tabulation Block Code The number of address that matched to a census address range in the particular block.

The output file format for the Address List:

Output Fields LINE NUMBER INPUT ADDRESS MATCH INDICATOR

MATCH TYPE

TIGER OUTPUT ADDRESS INTERPOLATED LONGITUDE, INTERPOLATED LATITUDE TIGERLINE ID

Definition The unique number for each address. The address submitted by the participant The results in this column refer to if the address matched a census address range (Match), did not match (No_Match), or was a tie between two or more Census address ranges (Tie). A Tie indicates multiple possible results for that address. Indicates if the match that occurred was exact (Exact), or equivocated (Equivocate.) The equivocated address that matched the TIGER address range. The interpolated Latitude and Longitude value based on the address range location, The specific TIGER Line Identifier number.

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