diff --git a/README.md b/README.md
index c5c3237..847827b 100644
--- a/README.md
+++ b/README.md
@@ -3,7 +3,10 @@
 [![pypi](https://img.shields.io/pypi/v/lsst-daf-relation.svg)](https://pypi.org/project/lsst-daf-relation/)
 [![codecov](https://codecov.io/gh/lsst/daf_relation/branch/main/graph/badge.svg?token=2BUBL8R9RH)](https://codecov.io/gh/lsst/daf_relation)
 
-`daf_relation` is a package in the [LSST Science Pipelines](https://pipelines.lsst.io).
+`daf_relation` was a package in the [LSST Science Pipelines](https://pipelines.lsst.io).
+It was formerly used to implement the query system in [daf_butler](https://github.com/lsst/daf_butler/).
+
+**As of November 2025, this package is no longer used or maintained.**
 
 This package provides classes that represent relational algebra expression trees, along with algorithms to convert them to SQLAlchemy objects and Python generators.