Sourcing reliable and up-to-date national parcel data can be a daunting task. Which provider has the best coverage? Does this parcel data have comprehensive attributes and full polygons? What are the advantages of paying for parcel data?
Our data experts help break down the key questions and considerations to consider when selecting a national parcel data provider.
Compare National Parcel Providers
When comparing parcel data providers there are four key things to consider:
- Coverage: What percentage of counties are covered?
- Attributes: What level of detail is provided for each county?
- Updates: How often are polygons and attributes updated by county?
- Cost: Free data can often cost time and resources to acquire and normalize the data
Parcel Data Coverage
The first thing to request from a potential parcel data provider is their coverage spreadsheet. Within the spreadsheet, each county should be listed along with the percent of parcel polygons provided, relevant attributes and the percent coverage of each attribute. It’s necessary to have this level of granularity from a parcel vendor in order to understand what data will be provided and assess how this will meet the needs of your project.
The next step is understanding how the vendor’s coverage map is defined. Data providers should be able to clarify for what percentage of a county they have coverage. Oftentimes, overlap occurs for neighboring counties. Some companies will include these as highlighted counties, when in reality they may only have 1% coverage in that county. Vendors should clarify where parcel polygons are available, as opposed to only centroids. If your project requires parcel polygons, centroids will not be useful to you.
Comprehensive Parcel Data Attributes
Each data vendor should have a comprehensive list of attributes available for each county, but it’s also important that they provide the percentage of attributes they provide for each county. It’s common for parcel data providers to share the number of counties that make up their coverage, but they rarely show the completeness of attribute coverage on a per-county basis.
Does the provider have the owner’s name? Site address? Acreage? Elevation? Mailing address? It’s important to know the completeness of a given attribute to avoid having to supplement missing data from another vendor, which may cost more time and money. For example, instead of a simple “yes” to indicate that the Owner’s Name is available in Jackson County, MO, you’ll want to know if 2% or 98% of all records in that county have this information available.
Accurate & Updated Parcel Data
Once you have a comprehensive understanding of parcel data coverage and attributes by county, the next crucial piece to understand is when the data requested was last updated.
Ask simple questions like, how often is your data updated? Is data updated for both parcel polygons and data attributes? Once you have determined the current vintage of the polygons as well as the attributes, the next question to ask is how often are parcel polygons and attributes updated? Some vendors will update data attributes annually, but only update parcel polygons every few years.
Asking your parcel data provider to provide detailed information about when and how data is updated is just as important as having attributes, polygons and coverage spreadsheets. There is a risk that if data is not updated, it may no longer be accurate, which can delay your project or planning.
Currently at ReportAll USA, 70% of counties are updated every 6 months. An additional 20% of counties are updated annually, and fewer than 10% of our counties are more than a year old (as of June 2020). All county updates are designed to include both parcel polygons as well as data attributes. Within the ReportAll Data Store you can download updates for up to 6 months with no additional fees.
6 Questions to Ask Your National Parcel Data Partner:
- Ask for a coverage spreadsheet by county?
- Clarify coverage by county; does this include polygons or centroids?
- What percentage of the county does the data set contain?
- Which attributes do you include for each county?
- How frequently is data updated?
- Are data updates inclusive of parcel polygons, attributes or both?
The ReportAll Advantage – Data Accuracy & Transparency
Having accurate and comprehensive data coverage spreadsheets allows you to compare national parcel layers one-to-one and assess viability for the needs of your project. Oftentimes county assessors will offer free parcel downloads, but they come in different formats, styles and level of detail, and typically require much processing and normalization before loading into your operating platform. Splicing the data together into a uniform document can take time, effort and money, and often leads to less than favorable results due to inconsistencies in attribute formatting across data sources. Learn more about the cost of free parcel property line data and you’ll soon come to realize that free isn’t really free when you factor in the time required to complete the merging and normalization process.
The ReportAll Data Store is available 24/7 and provides 97.7% coverage of the U.S. in a normalized format that is ready to be loaded directly into your operating platform. Users are able to access and download the data for 10 counties in less than 10 minutes in a uniform format that is easy to digest and utilize for next steps. Our parcel data spreadsheet is available for users at any time on our County Coverage landing page. Hover over any data attribute title to determine the attribute population for the entire National File Layer.
More detailed spreadsheets are available to organizations with a signed Non-disclosure Agreement in place. We are always open to having a discussion about how our National Parcel Layer can be used to meet your needs, so while you’re focused on your projects, let us worry about acquiring and normalizing the data for you.