Based on my understanding of the docs, yes, they are stored in the same region. The docs mention: "Backups are incremental and Copy-on-Write,". That suggests that backups are tied to the same storage infrastructure as your volume. Also, backups are restored to the same region as your volume, which also strengthens the case that they are in the same region.

Source: https://docs.railway.com/volumes/backups

Adding to darseen's, the copy-on-write detail is actually stronger evidence than it looks. a CoW snapshot doesn't copy your data, it references the same underlying blocks as the live volume and only stores what's changed since. blocks can't be shared across regions, so a CoW backup physically has to sit on the same storage as the volume it came from. the docs also note backups can only be restored into the same project and environment, which fits.

so technically, yes, EU West volume means EU West backups.

that said, if this is for GDPR or a DPA rather than curiosity, i wouldn't rely on a community inference from a pricing paragraph. the backups page doesn't state residency anywhere, so there's nothing you could point an auditor or customer at. worth asking railway for written confirmation that volume backups never leave the volume's region, and checking whether their DPA and subprocessor list covers it: https://docs.railway.com/enterprise/compliance

that's the piece that would actually hold up if someone asks you to evidence it.