Upcoming change to geolocation metro code values

On December 1, 2026, at 09:00 UTC, our geolocation data vendor will be releasing an update. This update will result in US metro_code values changing. References: Go , JavaScript , C++ , Fastly VCL Variable and Rust SDK What’s changing? Customers who use client.geo.metro_code in Varnish Configuration Language (VCL) or metro_code in the Compute Software Development Kits (SDKs) will see three-digit Designated Market Area (DMA) codes become five-digit Census Core Based Statistical Area (CBSA) codes. Locations with no CBSA match will return a value of 0. What’s next? What do I have to do? Customers who have hard-coded logic based on metro code values should revise that logic to use the new CBSA codes, and make sure their systems can handle five-digit US metro_code values and a value of 0 where no CBSA match exists. Customers should also review any workflows that rely on DMA-based groupings. We don't recommend building load-bearing logic on metro_code values. To learn more about CBSA codes, please read FIPS Metropolitan Area (CBSA) Codes and United States Census Bureau . Customers with any questions or concerns may engage with our Support team through https://support.fastly.com or by contacting your designated account management team members.