diff --git a/docs/api/tree.md b/docs/api/tree.md
index b9be327a7..59b715276 100644
--- a/docs/api/tree.md
+++ b/docs/api/tree.md
@@ -1,2 +1,3 @@
 ::: textual.widgets.Tree
 ::: textual.widgets._tree.TreeNode
+::: textual.widgets._tree.NodeID
diff --git a/src/textual/widgets/_tree.py b/src/textual/widgets/_tree.py
index 27f28b034..42d38c3cc 100644
--- a/src/textual/widgets/_tree.py
+++ b/src/textual/widgets/_tree.py
@@ -26,6 +26,8 @@ if TYPE_CHECKING:
     from typing_extensions import TypeAlias
 
 NodeID = NewType("NodeID", int)
+"""The type of an ID applied to a [TreeNode][textual.widgets._tree.TreeNode]."""
+
 TreeDataType = TypeVar("TreeDataType")
 EventTreeDataType = TypeVar("EventTreeDataType")