diff --git a/morpc/req.py b/morpc/req.py
index 7ae745a..4fed0d0 100644
--- a/morpc/req.py
+++ b/morpc/req.py
@@ -51,8 +51,12 @@ def get_json_safely(url, params=None, headers=default_headers, session: Session
             else:
                 json = r.json()
         else:
-            logger.error(f"Request failed. Content: {r.content}")
-            raise HTTPError(f"Request failed with status {r.status_code}: {r.url}")
+            # 204 means the request was valid but there is nothing to return, which callers may treat as no rows.
+            if r.status_code == 204:
+                logger.warning(f"No content returned: {r.url}")
+            else:
+                logger.error(f"Request failed. Content: {r.content}")
+            raise HTTPError(f"Request failed with status {r.status_code}: {r.url}", response=r)
     else:
         logger.debug(f"Request successful. Decoding return JSON.")
         try:
diff --git a/tests/test_req.py b/tests/test_req.py
index c21dbcd..8c43c41 100644
--- a/tests/test_req.py
+++ b/tests/test_req.py
@@ -32,5 +32,12 @@ def test_get_json_safely_raises_http_error_on_failed_request():
         get_json_safely("http://example", session=_FakeSession(_Response(400)))
 
 
+def test_get_json_safely_http_error_carries_response():
+    # Callers can tell "no content" (204, e.g. a Census geography with no data for a year) from a failure.
+    with pytest.raises(HTTPError) as excinfo:
+        get_json_safely("http://example", session=_FakeSession(_Response(204)))
+    assert excinfo.value.response.status_code == 204
+
+
 def test_get_json_safely_returns_json_on_success():
     assert get_json_safely("http://example", session=_FakeSession(_Response(200, [["a"], ["1"]]))) == [["a"], ["1"]]