Almost all of ATTOM's property data is associated with a specific property or a geographic area. When it comes to properties we assign a permanent unique identifier known as an ATTOM ID to the record, thereby making it easier to locate and match those records. For geographic areas, we use a geocode or geoid.

Because ATTOM has acquired several companies that have sold data for geographic areas we have multiple geocodes that can be used to identify the same geographic area. This adds a layer of complexity we do not want, but it will take us time to standardize and simplify this without impacting our existing customers.

Many of the ATTOM APIs return the geoids as part of the results for individual properties. This helps to place the property within specific geographic boundaries of interest.


ATTOM's original system for geocoding geographic areas in ATTOM API is referred to as "geoid". This coding system allows for the identification of the geography type as well as a value that uniquely identifies the geography itself. The following is an example of the geoids returned for a single property

"geoid": "CO08031, CS0891007, DB0803360, ND0000119198, ND0004861239, PL0820000, SB0000076114, SB0000076155, SB0000076161, SB0000135819, SB0000143772, ZI80212"

The first two characters are a code for the type (or class) of the geographic area -

CO - County
CS - County subdivision
DB - School district
ND - Neighborhood (all levels)
PL - Place
SB - School attendance area
ZI - Zip code tabulation area

The remaining characters uniquely identify the geographic areas within that class of geography. e.g. CO08031 can be taken to mean this property is located in a county whose code of 08031 will uniquely identify it from any other county.


As ATTOM consolidates its data into a single data warehouse so as to simplify the task of combining a comprehensive portfolio of property data, our systems are no longer maintaining this original geocoding. We will continue to make geoid available to support existing code, but over time new and existing properties may no longer have accurate values and new geographic areas may not be included. We are therefore encouraging our customers to migrate to using GeoIdv4 (see below).


"geoIdV4": {
          "CS": "4c0507d0d7894d2d48e4e03e1c0240fc",
          "N1": "b26d02d9330761156fc0cfd4ed8bf9a1",
          "PL": "7de845f7ba9b234a2c5adfca1db76c64",
          "ZI": "0149d0a55ef2d6b71071a39f4e13d6eb",
          "N2": "27e220314436f6edd5e606ddcd28156d"

The new geo-coding scheme provides a set of two values. The first is a two-character code that identifies the geography type. This is needed so that a program can interpret the data and easily find a specific type of geography. These are an expansion of the codes used in geoid -

CO - County
CS - County subdivision
DB - School district
N1 - Macro Neighborhood
N2 - Neighborhood
N3 - Sub-Neighborhood
N4 - Residential Subdivision
PL - Place
SB - School attendance area
ZI - Zip code tabulation area

The second value is a 32-character code that uniquely identifies the geographic area across all geography types. It is essentially the key for all geographic areas and corresponds to the keys assigned to boundary shape files. This is the value that should be used when requesting data for a geographic area.

Note: GeoIdv4 is only supported for ATTOM API endpoints that are version 4.0 or above.

Using Geocodes

When using an endpoint that requires the use of geocodes, both geoid and geoIDv4 can be used. We would strongly recommend the use of geoIdv4 (32-character code) moving forward. The original geoid should be considered deprecated.

For example:

Location Lookup

A new endpoint has been added to ATTOM API to assist with the adoption of the new geocodes. Location Lookup will accept text found in the description of an area and provide the geocodes (GeoIDV4) for each area that contains that text.

For example:, MA

Returns a list of the postal cities (CI) containing the text "Boston, MA", including the values to be used for geoIDV4.

    "status": {
        "version": "4",
        "code": 0,
        "msg": "SuccessWithResult",
        "total": 3,
        "page": 1,
        "pageSize": 10,
        "transactionID": "cbfd5d10e27d2d51d6284a16b7d9eb16"
    "geographies": [
            "geoIdV4": "6fdb3ee746e7a63e426d5fe852bdad2d",
            "geographyName": "East Boston, MA",
            "geographyTypeName": "Postal City",
            "geographyTypeAbbreviation": "CI",
            "details": {
                "name": "East Boston",
                "totalResidentCount": 14737,
                "multiFamilyDeliveryUnitCount": 6065,
                "singleFamilyDeliveryUnitCount": 8077,
                "poBoxCount": 595,
                "businessCount": 1116,
                "areaSquareMiles": 6.20965049319617,
                "longitude": -71.023906,
                "latitude": 42.371903
            "geoIdV4": "a50c236f2013a3cb6118d0a1840151aa",
            "geographyName": "Boston, MA",
            "geographyTypeName": "Postal City",
            "geographyTypeAbbreviation": "CI",
            "details": {
                "name": "Boston",
                "totalResidentCount": 68927,
                "multiFamilyDeliveryUnitCount": 62179,
                "singleFamilyDeliveryUnitCount": 5338,
                "poBoxCount": 1410,
                "businessCount": 13330,
                "areaSquareMiles": 6.75616554440227,
                "longitude": -71.064589,
                "latitude": 42.348866
            "geoIdV4": "f1bc4c3df9e6b60d1c10be1f378759cb",
            "geographyName": "South Boston, MA",
            "geographyTypeName": "Postal City",
            "geographyTypeAbbreviation": "CI",
            "details": {
                "name": "South Boston",
                "totalResidentCount": 15813,
                "multiFamilyDeliveryUnitCount": 8347,
                "singleFamilyDeliveryUnitCount": 7272,
                "poBoxCount": 194,
                "businessCount": 964,
                "areaSquareMiles": 2.48782708935132,
                "longitude": -71.036031,
                "latitude": 42.33367

Legacy GeoId Lookup

A new endpoint has been added to handle situations in which you may have an old geocode stored somewhere and you need to convert that to geoIDV4 before calling an endpoint supporting the new geocodes.

Would return the equivalent value of GeoIDV4 for County CO44003

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