Day 27 of the 30 Day Map Challenge and today's theme is "boundaries".
Map lines of division—political, physical, ecological, or conceptual. Explore the meaning and impact of a dividing line, real or perceived.
For today's challenge, I thought I'd make some resources available for people to use in their own reports.
There are a couple of challenges with mapping boundaries representing areas in Power BI maps that we can overcome with Icon Map Slicer.
Number of areas. With the out of the box visuals limited to 30000 rows, we often have more administrative areas than that. Icon Map Slicer enables us to set a higher maximum row count.
Complexity of geometry leading to large file sizes. Drawing over 30,000 administrative areas on the map can mean the source GeoJSON file sizes can be in the gigabytes - too large to upload inside a Power BI's visualisation layer, and even as Well Known Text (WKT), the shapes can be too complex to store within Power BI's dataset. In Icon Map Slicer, we provide PMTiles vector tile integration, so the file can sit on Azure Blob Storage and we only show the complexity required for that zoom level.
I've created a set of files for the latest versions of some the common UK geographies that you can use in Icon Map Slicer:
** Health **
- NHS England Regions : https://styles.iconmappro.com/catalog/ons/boundaries/NHS_England_Regions_JAN_2024.pmtiles
- Cancer Alliances : https://styles.iconmappro.com/catalog/ons/boundaries/Cancer_Alliances_July_2023.pmtiles
- Integrated Care Boards : https://styles.iconmappro.com/catalog/ons/boundaries/Integrated_Care_Boards_April_2023.pmtiles
** Blue Light Services **
- Fire and Rescue Authorities :
https://styles.iconmappro.com/catalog/ons/boundaries/Fire_And_Rescue_Authorities_Dec_2023.pmtiles - Police Force Areas :
https://styles.iconmappro.com/catalog/ons/boundaries/Police_Force_Areas_Dec_2023.pmtiles
** Administrative and Census **
- Local Authority Districts :
https://styles.iconmappro.com/catalog/ons/boundaries/LAD_MAY_2025_UK.pmtiles - Middle-Layer Super Output Areas :
https://styles.iconmappro.com/catalog/ons/boundaries/MSOA_DEC_2021.pmtiles - Lower-Layer Super Output Areas :
https://styles.iconmappro.com/catalog/ons/boundaries/LSOA_2021.pmtiles - Super Output Areas :
https://styles.iconmappro.com/catalog/ons/boundaries/OA_2021.pmtiles - Wards :
https://styles.iconmappro.com/catalog/ons/boundaries/Wards_May_2025.pmtiles
These are based on ONS open data and require the following attribution: Source: Office for National Statistics licensed under the Open Government Licence v.3.0. Contains OS data © Crown copyright and database right 2025
Here's a video to walk you through the process of using them - in this case with Lower Super Output Area Boundaries:
Here's the resulting Power BI report:
And the .pbix file to download.