diff --git a/pystac/extensions/label.py b/pystac/extensions/label.py
index 5ad899dff..9ce92db20 100644
--- a/pystac/extensions/label.py
+++ b/pystac/extensions/label.py
@@ -403,7 +403,6 @@ def merge_counts(self, other: "LabelOverview") -> "LabelOverview":
         """
         assert self.property_key == other.property_key
 
-        new_counts = None
         if self.counts is None:
             new_counts = other.counts
         else:
diff --git a/pystac/serialization/common_properties.py b/pystac/serialization/common_properties.py
index de9abe563..8ebcc7c27 100644
--- a/pystac/serialization/common_properties.py
+++ b/pystac/serialization/common_properties.py
@@ -29,7 +29,6 @@ def merge_common_properties(
     properties_merged = False
 
     collection: Optional[Union[pystac.Collection, Dict[str, Any]]] = None
-    collection_id: Optional[str] = None
     collection_href: Optional[str] = None
 
     stac_version = item_dict.get("stac_version")
@@ -79,7 +78,6 @@ def merge_common_properties(
                     collection = pystac.StacIO.default().read_json(collection_href)
 
     if collection is not None:
-        collection_id = None
         collection_props: Optional[Dict[str, Any]] = None
         if isinstance(collection, pystac.Collection):
             collection_id = collection.id
diff --git a/pystac/validation/schema_uri_map.py b/pystac/validation/schema_uri_map.py
index 8cfb223b0..f217f2f2b 100644
--- a/pystac/validation/schema_uri_map.py
+++ b/pystac/validation/schema_uri_map.py
@@ -77,7 +77,6 @@ class DefaultSchemaUriMap(SchemaUriMap):
     def _append_base_uri_if_needed(cls, uri: str, stac_version: str) -> Optional[str]:
         # Only append the base URI if it's not already an absolute URI
         if "://" not in uri:
-            base_uri = None
             for version_range, f in cls.BASE_URIS:
                 if version_range.contains(stac_version):
                     base_uri = f(stac_version)
@@ -91,7 +90,6 @@ def _append_base_uri_if_needed(cls, uri: str, stac_version: str) -> Optional[str
     def get_object_schema_uri(
         self, object_type: STACObjectType, stac_version: str
     ) -> Optional[str]:
-        uri = None
         is_latest = stac_version == pystac.get_stac_version()
 
         if object_type not in self.DEFAULT_SCHEMA_MAP:
@@ -315,7 +313,6 @@ def _append_base_uri_if_needed(
     ) -> Optional[str]:
         # Only append the base URI if it's not already an absolute URI
         if "://" not in uri:
-            base_uri = None
             for version_range, f in cls.get_base_uris():
                 if version_range.contains(stac_version):
                     base_uri = f(stac_version)