diff --git a/CHANGELOG.md b/CHANGELOG.md
index d3148bc..baa9ec8 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -9,6 +9,10 @@ This project uses [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 ## [Unreleased]
 
+### Security
+
+- **The Census API key is no longer written to logs.** `geoinfo_from_params()` logged its request parameters at INFO after adding `key`, so the key appeared in notebook outputs (hundreds of times per call through the hierarchical geography lookup). It now logs before adding the key. Keys passed on to `morpc.req` are redacted there from morpc 0.7.5 (morpc/morpc-py#207).
+
 ## [0.6.4] — 2026-09-23
 
 ### Fixed
diff --git a/morpc_census/geos.py b/morpc_census/geos.py
index 0593342..a922412 100644
--- a/morpc_census/geos.py
+++ b/morpc_census/geos.py
@@ -486,9 +486,10 @@ def geoinfo_from_params(param_dict: dict, year: int = 2024, output: Literal['lis
         if 'in' in param_dict:
             params.update({'in': param_dict['in']})
 
+    # Log before adding the API key, so the key never reaches logs or notebook outputs.
+    logger.info(f"Getting GEOIDS from {url} and params: {params}.")
     if k := _get_api_key():
         params['key'] = k
-    logger.info(f"Getting GEOIDS from {url} and params: {params}.")
     json = morpc.req.get_json_safely(url, params=params)
 
     if output == 'list':
diff --git a/tests/test_geos_hierarchical.py b/tests/test_geos_hierarchical.py
index bde2a15..92f1328 100644
--- a/tests/test_geos_hierarchical.py
+++ b/tests/test_geos_hierarchical.py
@@ -111,3 +111,16 @@ def test_county_subdivision_parts_pair_each_county_with_its_own_subdivisions():
         ("county subdivision:18000", "county:049", "state:39"),
     ]
     assert len(result) == 3
+
+
+def test_geoinfo_from_params_does_not_log_the_api_key(caplog):
+    # The key is sent with the request but must never reach the logs, which end up in committed
+    # notebook outputs. See #7.
+    from morpc_census.geos import geoinfo_from_params
+    secret = "s3cr3t-api-key"
+    caplog.set_level("DEBUG")
+    with patch("morpc_census.geos._get_api_key", return_value=secret), \
+         patch("morpc.req.get_json_safely", return_value=[["GEO_ID", "NAME"], ["1600000US3918000", "Columbus"]]) as mock:
+        geoinfo_from_params({"for": "place:18000", "in": "state:39"})
+    assert mock.call_args.kwargs["params"]["key"] == secret
+    assert secret not in caplog.text