Tuesday, June 18, 2013

Show & Tell for Module 7: Parcel Data

In this "Show & Tell" session, I'll show you some useful things that were not included in  LAD module 7.

If you'd like you can try these yourself. The data is included in the Challenge7 zip file which you can download and unzip. Here are the notes to re-create what I show you.


One of the functions of county government is to manage land ownership and to collect property taxes. Each of the four counties in Hawaii has a Real Property group that manages the data necessary to provide this function. Parcel data will be important in our project as a reference layer for both owner names and addresses.

In this example I have selected a small set of parcels in Kihei, Maui. The data is from 2006 which will work for our example. In the project you will use current parcel data. Let's start with the map of parcel features.

I have drawn the parcel features (polygons) with no color inside and a purple outline. Let's look at the parcel features table:

You can see the TMK field. Each parcel feature has a unique TMK (Tax Map Key) that identifies that parcel and can be used to relate to other data tables.

The OWNER field lists an owner of the parcel. As you saw in our previous Show & Tell on table joins and relates, one parcel can have multiple owners. We'll look at the owner database next, but for now, note that any OWNER value that ends in "/etal" (lower case letters) means that there are two or more actual owners.


Let's look at the OWNER table now.

This is data for all of the owners. Note that while there were 1,447 parcel records, there are 4,633 owner records. You can see that parcel 222023001 has two owners, Maybeline and Martin. Note that in the parcel table above you only see Maybeline's name along with "/etal". Again, the "/etal" indicates that you need to refer to the owner table to see all the owner names.

The other field here is TMKFULL. Note that the first nine digits are the same as the TMK. The last four digits (sometimes called CPRs or HPRs) are used to identify units within the parcel. For example, a condo parcel might have several dozen units, in which case the last four digits will be 0000, 0001, 0002, 0003 etc. In the table above there is only a single unit for TMK 222023001 with two owners so the last four digits are 0000.

Scrolling further down in the table, here is an example of records with different CPRs.

Note that the TMK is the same, 238077001, for all the records. On the map this is a single parcel, a single map feature. Looking at CPR 0000 we can see that within this parcel is the "Kihei Villages Phase I" project. Then you can see the owners of the different units. Note that some units, like CPR 0001, have only one owner. Other units, like CPR 0003, has two owners.


All of the owners in the above table are Fee title owners, meaning they own the land. There is a separate table for those owners who only hold the LEASEHOLD interest.

Most owners are fee owners in this area, there are only 28 leasehold owners in this area. Each record has a TMKFULL value which can be used to relate different tables. Note that a parcel with leasehold owners will also have one or more records for fee owners.


Each parcel has an assessed value for the land and for the building(s). The VALUES table contains this information.

In addition to the land and building values, there is also a field HOMEOWNER that indicates whether the owner lives on the property. Let's scroll down and look at the same CPR records in this table.

The CPR 0000 record is the master record for the project and shows the value of the land held in common. The individual CPR records then show the amount of land value apportioned to each unit and the building value for each unit.

If you look back at the owner table above, note that CPR 0003 has two owners, however in this value table, CPR 0003 has only one record. The two owners jointly own this same unit.


Each parcel has a site address, or sometimes many addresses, for example a condo project. The site address is the address where the parcel or unit is located.

There are two addresses shown in the table - the TMKADDRESS which will include the unit number (if any), and the TMKGEOADDR which contains just the address part which is sometimes used for a process called geocoding. Let's scroll down to the same CPR records.

You can see the different unit numbers in TMKADDRESS that have been removed from TMKGEOADDR.


There is another table of addresses - mailing addresses. These are the addresses where the tax bill is mailed to. Sometimes it is the same as the site address and sometimes it is different.

You can see that, for example, the tax bill for 222023001 is mailed to Pittsburg, California. Let's look at the rest of the table.

You can also see that the tax bill for 222023002 is mailed to an address on Maui, but not to the site address.

This type of information will be very helpful to us in our project where we are trying to locate voter addresses.


Just as with the census blocks, when you zoom in close you'll start to notice that the parcel boundaries don't line up perfectly with the basemap features.

This is 2006 data and since then Maui County Real Property has been working to make their parcels more accurate spatially. Sometimes the basemap is inaccurate. Sometimes it's both. This will be an issue we have to deal with in our project.

You will need to use this parcel data for Challenge 7.

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