diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index b463ee42..2f450a9b 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -16,7 +16,7 @@ jobs:
     strategy:
       matrix:
         os: [Ubuntu]
-        python-version: ["3.9", "3.10", "3.11", "3.12", "3.13"]
+        python-version: ["3.10", "3.11", "3.12", "3.13"]
         sphinx-version:
           ["sphinx==6.0", "sphinx==6.2", "sphinx==7.0", "sphinx>=7.3"]
         include:
diff --git a/README.rst b/README.rst
index 354a79d9..fdd35942 100644
--- a/README.rst
+++ b/README.rst
@@ -17,7 +17,7 @@ docstrings formatted according to the NumPy documentation format.
 The extension also adds the code description directives
 ``np:function``, ``np-c:function``, etc.
 
-numpydoc requires Python 3.9+ and sphinx 6+.
+numpydoc requires Python 3.10+ and sphinx 6+.
 
 For usage information, please refer to the `documentation
 <https://numpydoc.readthedocs.io/>`_.
diff --git a/doc/install.rst b/doc/install.rst
index 2471b765..5d61010f 100644
--- a/doc/install.rst
+++ b/doc/install.rst
@@ -5,7 +5,7 @@ Getting started
 Installation
 ============
 
-This extension requires Python 3.9+, sphinx 6+ and is available from:
+This extension requires Python 3.10+, sphinx 6+ and is available from:
 
 * `numpydoc on PyPI <http://pypi.python.org/pypi/numpydoc>`_
 * `numpydoc on GitHub <https://github.com/numpy/numpydoc/>`_
diff --git a/numpydoc/cli.py b/numpydoc/cli.py
index 53335fdf..30daa3f5 100644
--- a/numpydoc/cli.py
+++ b/numpydoc/cli.py
@@ -4,14 +4,14 @@
 import ast
 from collections.abc import Sequence
 from pathlib import Path
-from typing import List, Union
+from typing import List
 
 from .docscrape_sphinx import get_doc_object
 from .hooks import utils, validate_docstrings
 from .validate import ERROR_MSGS, Validator, validate
 
 
-def render_object(import_path: str, config: Union[List[str], None] = None) -> int:
+def render_object(import_path: str, config: List[str] | None = None) -> int:
     """Test numpydoc docstring generation for a given object."""
     # TODO: Move Validator._load_obj to a better place than validate
     print(get_doc_object(Validator._load_obj(import_path), config=dict(config or [])))
@@ -117,7 +117,7 @@ def _parse_config(s):
     return ap
 
 
-def main(argv: Union[Sequence[str], None] = None) -> int:
+def main(argv: Sequence[str] | None = None) -> int:
     """CLI for numpydoc."""
     ap = get_parser()
 
diff --git a/numpydoc/docscrape.py b/numpydoc/docscrape.py
index 54863d5f..9cf5c5a9 100644
--- a/numpydoc/docscrape.py
+++ b/numpydoc/docscrape.py
@@ -701,7 +701,7 @@ def properties(self):
                 and not self._should_skip_member(name, self._cls)
                 and (
                     func is None
-                    or isinstance(func, (property, cached_property))
+                    or isinstance(func, property | cached_property)
                     or inspect.isdatadescriptor(func)
                 )
                 and self._is_show_member(name)
diff --git a/numpydoc/hooks/validate_docstrings.py b/numpydoc/hooks/validate_docstrings.py
index a718e4ef..70823f10 100644
--- a/numpydoc/hooks/validate_docstrings.py
+++ b/numpydoc/hooks/validate_docstrings.py
@@ -63,7 +63,7 @@ def name(self) -> str:
 
     @property
     def is_function_or_method(self) -> bool:
-        return isinstance(self.node, (ast.FunctionDef, ast.AsyncFunctionDef))
+        return isinstance(self.node, ast.FunctionDef | ast.AsyncFunctionDef)
 
     @property
     def is_mod(self) -> bool:
@@ -236,7 +236,7 @@ def visit(self, node: ast.AST) -> None:
             The node to visit.
         """
         if isinstance(
-            node, (ast.Module, ast.ClassDef, ast.FunctionDef, ast.AsyncFunctionDef)
+            node, ast.Module | ast.ClassDef | ast.FunctionDef | ast.AsyncFunctionDef
         ):
             self.stack.append(node)
 
@@ -395,8 +395,8 @@ def process_file(filepath: os.PathLike, config: dict) -> "list[list[str]]":
 def run_hook(
     files: List[str],
     *,
-    config: Union[Dict[str, Any], None] = None,
-    ignore: Union[List[str], None] = None,
+    config: Dict[str, Any] | None = None,
+    ignore: List[str] | None = None,
 ) -> int:
     """
     Run the numpydoc validation hook.
diff --git a/numpydoc/numpydoc.py b/numpydoc/numpydoc.py
index 9c1bb0ed..b1431519 100644
--- a/numpydoc/numpydoc.py
+++ b/numpydoc/numpydoc.py
@@ -88,7 +88,7 @@ def _is_cite_in_numpydoc_docstring(citation_node):
     section_node = citation_node.parent
 
     def is_docstring_section(node):
-        return isinstance(node, (section, desc_content))
+        return isinstance(node, section | desc_content)
 
     while not is_docstring_section(section_node):
         section_node = section_node.parent
diff --git a/numpydoc/tests/test_docscrape.py b/numpydoc/tests/test_docscrape.py
index c122515a..dbfc5c14 100644
--- a/numpydoc/tests/test_docscrape.py
+++ b/numpydoc/tests/test_docscrape.py
@@ -187,7 +187,9 @@ def test_extended_summary(doc):
 def test_parameters(doc):
     assert len(doc["Parameters"]) == 4
     names = [n for n, _, _ in doc["Parameters"]]
-    assert all(a == b for a, b in zip(names, ["mean", "cov", "shape"]))
+    assert all(
+        a == b for a, b in zip(names, ["mean", "cov", "shape", "dtype"], strict=True)
+    )
 
     arg, arg_type, desc = doc["Parameters"][1]
     assert arg_type == "(N, N) ndarray"
@@ -242,7 +244,9 @@ def test_yields():
         ("b", "int", "bananas."),
         ("", "int", "unknowns."),
     ]
-    for (arg, arg_type, desc), (arg_, arg_type_, end) in zip(section, truth):
+    for (arg, arg_type, desc), (arg_, arg_type_, end) in zip(
+        section, truth, strict=True
+    ):
         assert arg == arg_
         assert arg_type == arg_type_
         assert desc[0].startswith("The number of")
@@ -253,7 +257,9 @@ def test_sent():
     section = doc_sent["Receives"]
     assert len(section) == 2
     truth = [("b", "int", "bananas."), ("c", "int", "oranges.")]
-    for (arg, arg_type, desc), (arg_, arg_type_, end) in zip(section, truth):
+    for (arg, arg_type, desc), (arg_, arg_type_, end) in zip(
+        section, truth, strict=True
+    ):
         assert arg == arg_
         assert arg_type == arg_type_
         assert desc[0].startswith("The number of")
@@ -374,7 +380,7 @@ def line_by_line_compare(a, b, n_lines=None):
     a = [l.rstrip() for l in _strip_blank_lines(a).split("\n")][:n_lines]
     b = [l.rstrip() for l in _strip_blank_lines(b).split("\n")][:n_lines]
     assert len(a) == len(b)
-    for ii, (aa, bb) in enumerate(zip(a, b)):
+    for ii, (aa, bb) in enumerate(zip(a, b, strict=True)):
         assert aa == bb
 
 
diff --git a/numpydoc/validate.py b/numpydoc/validate.py
index d0debfa2..18373b77 100644
--- a/numpydoc/validate.py
+++ b/numpydoc/validate.py
@@ -17,7 +17,7 @@
 import textwrap
 import tokenize
 from copy import deepcopy
-from typing import Any, Dict, List, Optional, Set
+from typing import Any, Dict, List, Set
 
 from .docscrape import get_doc_object
 
@@ -124,7 +124,7 @@ def _unwrap(obj):
 # and pandas, and they had between ~500 and ~1300 .py files as of 2023-08-16.
 @functools.lru_cache(maxsize=2000)
 def extract_ignore_validation_comments(
-    filepath: Optional[os.PathLike],
+    filepath: os.PathLike | None,
     encoding: str = "utf-8",
 ) -> Dict[int, List[str]]:
     """
diff --git a/pyproject.toml b/pyproject.toml
index b6acaa4c..c8158115 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -6,7 +6,7 @@ requires = ['setuptools>=61.2']
 name = 'numpydoc'
 description = 'Sphinx extension to support docstrings in Numpy format'
 readme = 'README.rst'
-requires-python = '>=3.9'
+requires-python = '>=3.10'
 dynamic = ['version']
 keywords = [
     'sphinx',
@@ -20,7 +20,6 @@ classifiers = [
     'Operating System :: OS Independent',
     'Programming Language :: Python',
     'Programming Language :: Python :: 3',
-    'Programming Language :: Python :: 3.9',
     'Programming Language :: Python :: 3.10',
     'Programming Language :: Python :: 3.11',
     'Programming Language :: Python :: 3.12',