The parcel data pipeline
- A deed or plat is recorded at the county recorder.
- The assessor updates the tax roll and assigns or updates the APN.
- The GIS office redraws the affected polygons on the parcel map.
- The public portal publishes the updated parcel record.
- Aggregators like Landy normalize the data into a single national view.
Why quality varies between counties
- Metro counties have full time GIS teams. Rural counties may have one analyst part time.
- Newer subdivisions are drawn from clean digital plats. Older parcels are redrawn from scanned plats and metes and bounds.
- Update schedules range from real time to a few times a year.
- State law dictates what counties must publish. Some are aggressive about open data; others are not.
- Software changes break links and refresh cycles, which is why portals occasionally fall behind.
What this means for your research
Treat parcel polygons as approximate by default. Trust them more when the underlying plat is recent and the county has an active GIS program. Trust them less when the parcel is old, rural, or near a recent split. Always cross check the deed for legal description and the tax bill for the current APN.
How aggregators help
A nationwide app like Landy pulls many county feeds into one searchable map. That solves the discovery problem: you do not need to know which portal hosts which county. It does not solve the accuracy problem; the underlying data is still owned by the county. Use the app to research efficiently, and follow the source links when stakes are high.
Key takeaways
- Parcel data is built and published county by county, on local schedules.
- Newer urban polygons are crisp; older rural polygons drift more.
- Aggregators solve discovery, not accuracy. Confirm with the deed when it matters.