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How to Get Parcel GeoJSON Data from Your County GIS

By · Last updated April 26, 2026 · 8 min read

To use UrbanKit Studio's Radius Notice Generator, you need parcel polygon data in GeoJSON format. This guide covers the common ways to find and download that data for your jurisdiction.

Option 1: County GIS Open Data Portals

Many counties publish parcel data through open data portals. To find yours:

  1. Search: [Your County] GIS open data or [Your County] parcel data download
  2. Look for datasets labeled "Parcels," "Tax Parcels," or "Assessor Parcels"
  3. Check for download options. Look for GeoJSON, or Shapefile (which you can convert).
Common platforms: Many counties use ArcGIS Hub, Socrata, or CKAN for their open data. If you see these platforms, look for an "Export" or "Download" button on the dataset page.

What to look for in parcel data:

  • Polygon geometry: The actual parcel boundaries (required)
  • APN/Parcel ID: Unique identifier for each parcel
  • Owner name: For your mailing list
  • Mailing address: Street, city, state, ZIP (separate fields preferred)
  • Situs address: The property's physical address (nice to have)
Watch out: Some counties publish parcel boundaries without owner or mailing information for privacy reasons. You may need to join the geometry with a separate assessor table.

Option 2: State GIS Clearinghouses

Some states aggregate parcel data from all counties into a single statewide dataset:

  • California: No statewide parcel dataset (county by county)
  • Florida: Florida Geographic Data Library (FGDL)
  • Texas: Texas Natural Resources Information System (TNRIS)
  • Oregon: Oregon Spatial Data Library
  • Washington: Washington Geospatial Open Data Portal

Search: [Your State] GIS clearinghouse parcels

Option 3: Commercial Data Providers

If free sources don't have what you need, commercial providers offer cleaned, standardized parcel data:

  • Regrid (formerly Loveland Technologies): Nationwide parcel data, various pricing tiers
  • LightBox: Commercial parcel and property data
  • CoreLogic: Enterprise-level property data
  • Precisely (formerly Pitney Bowes): Parcel boundaries and attributes

These services charge per parcel or per county, and provide cleaner data with standardized field names.

Option 4: Request from Your County GIS Department

If public downloads aren't available, contact your county GIS or Assessor's office directly:

  1. Find the county GIS department contact (usually under "Departments" on the county website)
  2. Request parcel polygon data with owner and mailing information
  3. Specify GeoJSON or Shapefile format
  4. Ask about fees or data sharing agreements
For government staff: If you work for a city or agency, your county likely has a data sharing agreement. Check with your GIS coordinator; you may already have access.

Converting Shapefiles to GeoJSON

Many sources offer only Shapefile format. To convert:

Using mapshaper.org (Free, Online)

  1. Go to mapshaper.org
  2. Drag and drop ALL shapefile components (.shp, .dbf, .shx, .prj) at once
  3. Click "Export" in the top right
  4. Select "GeoJSON" and click Export

Using QGIS (Free, Desktop)

  1. Download and install QGIS
  2. Drag the shapefile into QGIS
  3. Right-click the layer → Export → Save Features As
  4. Select GeoJSON format, set CRS to EPSG:4326 (WGS84)
  5. Save

Data Quality Checklist

Before using your parcel data, verify:

  • ☐ Geometry: Parcels are polygons (not just points or centroids)
  • ☐ Coordinate system: WGS84 (EPSG:4326) or easily convertible
  • ☐ Owner names: Present and reasonably complete
  • ☐ Mailing addresses: All components present (street, city, state, ZIP)
  • ☐ Currency: Data is from the current assessment year
  • ☐ Coverage: Includes your project area

Common Issues and Solutions

File is too large?

County-wide datasets can run 50-200MB. Solutions:

  • Use mapshaper to clip to your project area
  • Simplify geometry (cuts precision but cuts file size more)
  • Split into smaller geographic chunks

Missing mailing addresses?

Some parcel datasets include geometry but not owner or mailing information. To fill the gap:

  • Find a separate assessor or owner table
  • Request the full assessor dataset (mailing addresses are often in a separate table)
  • Join parcel polygons to the owner or mailing address table by APN

Wrong coordinate system?

GeoJSON uses WGS84 (EPSG:4326). If your file uses a local projection, convert it using QGIS or mapshaper before uploading.

Ready to generate your mailing list?

Open the Radius Notice Generator →

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