diff --git a/lib/matplotlib/_api/__init__.py b/lib/matplotlib/_api/__init__.py
index cf27e68a4d2e..f251e07bab59 100644
--- a/lib/matplotlib/_api/__init__.py
+++ b/lib/matplotlib/_api/__init__.py
@@ -57,6 +57,46 @@ def fget(self):
         return self._fget
 
 
+# In the following check_foo() functions, the first parameter starts with an
+# underscore because it is intended to be positional-only (e.g., so that
+# `_api.check_isinstance([...], types=foo)` doesn't fail.
+
+def check_isinstance(_types, **kwargs):
+    """
+    For each *key, value* pair in *kwargs*, check that *value* is an instance
+    of one of *_types*; if not, raise an appropriate TypeError.
+
+    As a special case, a ``None`` entry in *_types* is treated as NoneType.
+
+    Examples
+    --------
+    >>> _api.check_isinstance((SomeClass, None), arg=arg)
+    """
+    types = _types
+    none_type = type(None)
+    types = ((types,) if isinstance(types, type) else
+             (none_type,) if types is None else
+             tuple(none_type if tp is None else tp for tp in types))
+
+    def type_name(tp):
+        return ("None" if tp is none_type
+                else tp.__qualname__ if tp.__module__ == "builtins"
+                else f"{tp.__module__}.{tp.__qualname__}")
+
+    for k, v in kwargs.items():
+        if not isinstance(v, types):
+            names = [*map(type_name, types)]
+            if "None" in names:  # Move it to the end for better wording.
+                names.remove("None")
+                names.append("None")
+            raise TypeError(
+                "{!r} must be an instance of {}, not a {}".format(
+                    k,
+                    ", ".join(names[:-1]) + " or " + names[-1]
+                    if len(names) > 1 else names[0],
+                    type_name(type(v))))
+
+
 def check_in_list(_values, *, _print_supported_values=True, **kwargs):
     """
     For each *key, value* pair in *kwargs*, check that *value* is in *_values*.
diff --git a/lib/matplotlib/axes/_base.py b/lib/matplotlib/axes/_base.py
index ae2e0c34141e..a6c6a18a5457 100644
--- a/lib/matplotlib/axes/_base.py
+++ b/lib/matplotlib/axes/_base.py
@@ -1075,7 +1075,7 @@ def sharex(self, other):
         axes, and cannot be used if the x-axis is already being shared with
         another axes.
         """
-        cbook._check_isinstance(_AxesBase, other=other)
+        _api.check_isinstance(_AxesBase, other=other)
         if self._sharex is not None and other is not self._sharex:
             raise ValueError("x-axis is already shared")
         self._shared_x_axes.join(self, other)
@@ -1094,7 +1094,7 @@ def sharey(self, other):
         axes, and cannot be used if the y-axis is already being shared with
         another axes.
         """
-        cbook._check_isinstance(_AxesBase, other=other)
+        _api.check_isinstance(_AxesBase, other=other)
         if self._sharey is not None and other is not self._sharey:
             raise ValueError("y-axis is already shared")
         self._shared_y_axes.join(self, other)
diff --git a/lib/matplotlib/axis.py b/lib/matplotlib/axis.py
index cc68386459a5..7ec16d04d2a2 100644
--- a/lib/matplotlib/axis.py
+++ b/lib/matplotlib/axis.py
@@ -1599,7 +1599,7 @@ def _set_formatter(self, formatter, level):
               not isinstance(formatter, mticker.TickHelper)):
             formatter = mticker.FuncFormatter(formatter)
         else:
-            cbook._check_isinstance(mticker.Formatter, formatter=formatter)
+            _api.check_isinstance(mticker.Formatter, formatter=formatter)
 
         if (isinstance(formatter, mticker.FixedFormatter)
                 and len(formatter.seq) > 0
@@ -1624,7 +1624,7 @@ def set_major_locator(self, locator):
         ----------
         locator : `~matplotlib.ticker.Locator`
         """
-        cbook._check_isinstance(mticker.Locator, locator=locator)
+        _api.check_isinstance(mticker.Locator, locator=locator)
         self.isDefault_majloc = False
         self.major.locator = locator
         if self.major.formatter:
@@ -1640,7 +1640,7 @@ def set_minor_locator(self, locator):
         ----------
         locator : `~matplotlib.ticker.Locator`
         """
-        cbook._check_isinstance(mticker.Locator, locator=locator)
+        _api.check_isinstance(mticker.Locator, locator=locator)
         self.isDefault_minloc = False
         self.minor.locator = locator
         if self.minor.formatter:
diff --git a/lib/matplotlib/backend_bases.py b/lib/matplotlib/backend_bases.py
index 5a7be04c4815..acbe52d77a3f 100644
--- a/lib/matplotlib/backend_bases.py
+++ b/lib/matplotlib/backend_bases.py
@@ -930,7 +930,7 @@ def set_clip_rectangle(self, rectangle):
 
     def set_clip_path(self, path):
         """Set the clip path to a `.TransformedPath` or None."""
-        cbook._check_isinstance((transforms.TransformedPath, None), path=path)
+        _api.check_isinstance((transforms.TransformedPath, None), path=path)
         self._clippath = path
 
     def set_dashes(self, dash_offset, dash_list):
diff --git a/lib/matplotlib/blocking_input.py b/lib/matplotlib/blocking_input.py
index fde7f30c5f38..afbfdacfdbd7 100644
--- a/lib/matplotlib/blocking_input.py
+++ b/lib/matplotlib/blocking_input.py
@@ -22,7 +22,7 @@
 import logging
 from numbers import Integral
 
-from matplotlib import cbook
+from matplotlib import _api
 from matplotlib.backend_bases import MouseButton
 import matplotlib.lines as mlines
 
@@ -78,7 +78,7 @@ def pop_event(self, index=-1):
 
     def __call__(self, n=1, timeout=30):
         """Blocking call to retrieve *n* events."""
-        cbook._check_isinstance(Integral, n=n)
+        _api.check_isinstance(Integral, n=n)
         self.n = n
         self.events = []
 
diff --git a/lib/matplotlib/category.py b/lib/matplotlib/category.py
index a4df76d438ab..2e7f19cd7a64 100644
--- a/lib/matplotlib/category.py
+++ b/lib/matplotlib/category.py
@@ -17,7 +17,7 @@
 
 import numpy as np
 
-from matplotlib import cbook, ticker, units
+from matplotlib import _api, ticker, units
 
 
 _log = logging.getLogger(__name__)
@@ -217,7 +217,7 @@ def update(self, data):
         convertible = True
         for val in OrderedDict.fromkeys(data):
             # OrderedDict just iterates over unique values in data.
-            cbook._check_isinstance((str, bytes), value=val)
+            _api.check_isinstance((str, bytes), value=val)
             if convertible:
                 # this will only be called so long as convertible is True.
                 convertible = self._str_is_convertible(val)
diff --git a/lib/matplotlib/cbook/__init__.py b/lib/matplotlib/cbook/__init__.py
index db89c9e4a16a..acc1320c3c9c 100644
--- a/lib/matplotlib/cbook/__init__.py
+++ b/lib/matplotlib/cbook/__init__.py
@@ -2242,47 +2242,6 @@ def _check_and_log_subprocess(command, logger, **kwargs):
     return proc.stdout
 
 
-# In the following _check_foo functions, the first parameter starts with an
-# underscore because it is intended to be positional-only (e.g., so that
-# `_check_isinstance([...], types=foo)` doesn't fail.
-
-
-def _check_isinstance(_types, **kwargs):
-    """
-    For each *key, value* pair in *kwargs*, check that *value* is an instance
-    of one of *_types*; if not, raise an appropriate TypeError.
-
-    As a special case, a ``None`` entry in *_types* is treated as NoneType.
-
-    Examples
-    --------
-    >>> cbook._check_isinstance((SomeClass, None), arg=arg)
-    """
-    types = _types
-    none_type = type(None)
-    types = ((types,) if isinstance(types, type) else
-             (none_type,) if types is None else
-             tuple(none_type if tp is None else tp for tp in types))
-
-    def type_name(tp):
-        return ("None" if tp is none_type
-                else tp.__qualname__ if tp.__module__ == "builtins"
-                else f"{tp.__module__}.{tp.__qualname__}")
-
-    for k, v in kwargs.items():
-        if not isinstance(v, types):
-            names = [*map(type_name, types)]
-            if "None" in names:  # Move it to the end for better wording.
-                names.remove("None")
-                names.append("None")
-            raise TypeError(
-                "{!r} must be an instance of {}, not a {}".format(
-                    k,
-                    ", ".join(names[:-1]) + " or " + names[-1]
-                    if len(names) > 1 else names[0],
-                    type_name(type(v))))
-
-
 def _backend_module_name(name):
     """
     Convert a backend name (either a standard backend -- "Agg", "TkAgg", ... --
diff --git a/lib/matplotlib/cm.py b/lib/matplotlib/cm.py
index 8383b9559416..2f1443d0f09f 100644
--- a/lib/matplotlib/cm.py
+++ b/lib/matplotlib/cm.py
@@ -136,7 +136,7 @@ def register_cmap(name=None, cmap=None, *, override_builtin=False):
     the registered colormap will be immutable.
 
     """
-    cbook._check_isinstance((str, None), name=name)
+    _api.check_isinstance((str, None), name=name)
     if name is None:
         try:
             name = cmap.name
@@ -448,7 +448,7 @@ def set_norm(self, norm):
         the norm of the mappable will reset the norm, locator, and formatters
         on the colorbar to default.
         """
-        cbook._check_isinstance((colors.Normalize, None), norm=norm)
+        _api.check_isinstance((colors.Normalize, None), norm=norm)
         in_init = self.norm is None
         if norm is None:
             norm = colors.Normalize()
diff --git a/lib/matplotlib/colorbar.py b/lib/matplotlib/colorbar.py
index 96be6cb8edbb..31d9b6176821 100644
--- a/lib/matplotlib/colorbar.py
+++ b/lib/matplotlib/colorbar.py
@@ -35,7 +35,7 @@
 import numpy as np
 
 import matplotlib as mpl
-from matplotlib import _api, cbook, collections, cm, colors, contour, ticker
+from matplotlib import _api, collections, cm, colors, contour, ticker
 import matplotlib.artist as martist
 import matplotlib.patches as mpatches
 import matplotlib.path as mpath
@@ -429,7 +429,7 @@ def __init__(self, ax, cmap=None,
                  extendrect=False,
                  label='',
                  ):
-        cbook._check_isinstance([colors.Colormap, None], cmap=cmap)
+        _api.check_isinstance([colors.Colormap, None], cmap=cmap)
         _api.check_in_list(
             ['vertical', 'horizontal'], orientation=orientation)
         _api.check_in_list(
diff --git a/lib/matplotlib/dviread.py b/lib/matplotlib/dviread.py
index 6f65de52b654..b55dacbb2eca 100644
--- a/lib/matplotlib/dviread.py
+++ b/lib/matplotlib/dviread.py
@@ -551,7 +551,7 @@ class DviFont:
     __slots__ = ('texname', 'size', 'widths', '_scale', '_vf', '_tfm')
 
     def __init__(self, scale, tfm, texname, vf):
-        cbook._check_isinstance(bytes, texname=texname)
+        _api.check_isinstance(bytes, texname=texname)
         self._scale = scale
         self._tfm = tfm
         self.texname = texname
diff --git a/lib/matplotlib/figure.py b/lib/matplotlib/figure.py
index 68d950e6247c..71be82de0374 100644
--- a/lib/matplotlib/figure.py
+++ b/lib/matplotlib/figure.py
@@ -122,7 +122,7 @@ def add(self, key, a):
         """
         # All the error checking may be unnecessary; but this method
         # is called so seldom that the overhead is negligible.
-        cbook._check_isinstance(Axes, a=a)
+        _api.check_isinstance(Axes, a=a)
         try:
             hash(key)
         except TypeError:
diff --git a/lib/matplotlib/rcsetup.py b/lib/matplotlib/rcsetup.py
index 3f273cbbee27..e68e6e4809eb 100644
--- a/lib/matplotlib/rcsetup.py
+++ b/lib/matplotlib/rcsetup.py
@@ -395,7 +395,7 @@ def validate_color(s):
 
 
 def _validate_cmap(s):
-    cbook._check_isinstance((str, Colormap), cmap=s)
+    _api.check_isinstance((str, Colormap), cmap=s)
     return s
 
 
@@ -770,7 +770,7 @@ def validate_hatch(s):
     """
     if not isinstance(s, str):
         raise ValueError("Hatch pattern must be a string")
-    cbook._check_isinstance(str, hatch_pattern=s)
+    _api.check_isinstance(str, hatch_pattern=s)
     unknown = set(s) - {'\\', '/', '|', '-', '+', '*', '.', 'x', 'o', 'O'}
     if unknown:
         raise ValueError("Unknown hatch symbol(s): %s" % list(unknown))
diff --git a/lib/matplotlib/spines.py b/lib/matplotlib/spines.py
index c00962de5a8a..40ceb157fd6e 100644
--- a/lib/matplotlib/spines.py
+++ b/lib/matplotlib/spines.py
@@ -4,7 +4,7 @@
 import numpy as np
 
 import matplotlib
-from matplotlib import _api, cbook, docstring, rcParams
+from matplotlib import _api, docstring, rcParams
 from matplotlib.artist import allow_rasterization
 import matplotlib.transforms as mtransforms
 import matplotlib.patches as mpatches
@@ -69,7 +69,7 @@ def __init__(self, axes, spine_type, path, **kwargs):
         # non-rectangular axes is currently implemented, and this lets
         # them pass through the spines machinery without errors.)
         self._position = None
-        cbook._check_isinstance(matplotlib.path.Path, path=path)
+        _api.check_isinstance(matplotlib.path.Path, path=path)
         self._path = path
 
         # To support drawing both linear and circular spines, this
diff --git a/lib/matplotlib/table.py b/lib/matplotlib/table.py
index eea686e4dd63..965cb6eeda9b 100644
--- a/lib/matplotlib/table.py
+++ b/lib/matplotlib/table.py
@@ -19,7 +19,7 @@
 Thanks to John Gill for providing the class and table.
 """
 
-from . import artist, cbook, docstring
+from . import _api, artist, docstring
 from .artist import Artist, allow_rasterization
 from .patches import Rectangle
 from .text import Text
@@ -342,7 +342,7 @@ def __setitem__(self, position, cell):
         """
         Set a custom cell in a given position.
         """
-        cbook._check_isinstance(Cell, cell=cell)
+        _api.check_isinstance(Cell, cell=cell)
         try:
             row, col = position[0], position[1]
         except Exception as err:
diff --git a/lib/matplotlib/transforms.py b/lib/matplotlib/transforms.py
index 8fdd49dbd010..bfc2915872c4 100644
--- a/lib/matplotlib/transforms.py
+++ b/lib/matplotlib/transforms.py
@@ -41,7 +41,7 @@
 import numpy as np
 from numpy.linalg import inv
 
-from matplotlib import _api, cbook
+from matplotlib import _api
 from matplotlib._path import (
     affine_transform, count_bboxes_overlapping_bbox, update_path_extents)
 from .path import Path
@@ -1054,7 +1054,7 @@ def __init__(self, bbox, transform, **kwargs):
         """
         if not bbox.is_bbox:
             raise ValueError("'bbox' is not a bbox")
-        cbook._check_isinstance(Transform, transform=transform)
+        _api.check_isinstance(Transform, transform=transform)
         if transform.input_dims != 2 or transform.output_dims != 2:
             raise ValueError(
                 "The input and output dimensions of 'transform' must be 2")
@@ -1660,7 +1660,7 @@ def __init__(self, child):
         *child*: A `Transform` instance.  This child may later
         be replaced with :meth:`set`.
         """
-        cbook._check_isinstance(Transform, child=child)
+        _api.check_isinstance(Transform, child=child)
         self._init(child)
         self.set_children(child)
 
@@ -1911,7 +1911,7 @@ def set(self, other):
         Set this transformation from the frozen copy of another
         `Affine2DBase` object.
         """
-        cbook._check_isinstance(Affine2DBase, other=other)
+        _api.check_isinstance(Affine2DBase, other=other)
         self._mtx = other.get_matrix()
         self.invalidate()
 
@@ -2686,7 +2686,7 @@ def __init__(self, path, transform):
         path : `~.path.Path`
         transform : `Transform`
         """
-        cbook._check_isinstance(Transform, transform=transform)
+        _api.check_isinstance(Transform, transform=transform)
         super().__init__()
         self._path = path
         self._transform = transform
diff --git a/lib/matplotlib/tri/trifinder.py b/lib/matplotlib/tri/trifinder.py
index 8cf3830125eb..e06b84c0d974 100644
--- a/lib/matplotlib/tri/trifinder.py
+++ b/lib/matplotlib/tri/trifinder.py
@@ -1,6 +1,6 @@
 import numpy as np
 
-from matplotlib import cbook
+from matplotlib import _api
 from matplotlib.tri import Triangulation
 
 
@@ -17,7 +17,7 @@ class TriFinder:
     """
 
     def __init__(self, triangulation):
-        cbook._check_isinstance(Triangulation, triangulation=triangulation)
+        _api.check_isinstance(Triangulation, triangulation=triangulation)
         self._triangulation = triangulation
 
 
diff --git a/lib/matplotlib/tri/triinterpolate.py b/lib/matplotlib/tri/triinterpolate.py
index 8c649d5c27fc..84674766f04d 100644
--- a/lib/matplotlib/tri/triinterpolate.py
+++ b/lib/matplotlib/tri/triinterpolate.py
@@ -4,7 +4,7 @@
 
 import numpy as np
 
-from matplotlib import _api, cbook
+from matplotlib import _api
 from matplotlib.tri import Triangulation
 from matplotlib.tri.trifinder import TriFinder
 from matplotlib.tri.tritools import TriAnalyzer
@@ -31,7 +31,7 @@ class TriInterpolator:
     """
 
     def __init__(self, triangulation, z, trifinder=None):
-        cbook._check_isinstance(Triangulation, triangulation=triangulation)
+        _api.check_isinstance(Triangulation, triangulation=triangulation)
         self._triangulation = triangulation
 
         self._z = np.asarray(z)
@@ -39,7 +39,7 @@ def __init__(self, triangulation, z, trifinder=None):
             raise ValueError("z array must have same length as triangulation x"
                              " and y arrays")
 
-        cbook._check_isinstance((TriFinder, None), trifinder=trifinder)
+        _api.check_isinstance((TriFinder, None), trifinder=trifinder)
         self._trifinder = trifinder or self._triangulation.get_trifinder()
 
         # Default scaling factors : 1.0 (= no scaling)
@@ -996,8 +996,7 @@ class _DOF_estimator:
     gradient coordinates.
     """
     def __init__(self, interpolator, **kwargs):
-        cbook._check_isinstance(
-            CubicTriInterpolator, interpolator=interpolator)
+        _api.check_isinstance(CubicTriInterpolator, interpolator=interpolator)
         self._pts = interpolator._pts
         self._tris_pts = interpolator._tris_pts
         self.z = interpolator._z
diff --git a/lib/matplotlib/tri/tripcolor.py b/lib/matplotlib/tri/tripcolor.py
index 67cb0f3c9079..f1f7de2285dc 100644
--- a/lib/matplotlib/tri/tripcolor.py
+++ b/lib/matplotlib/tri/tripcolor.py
@@ -1,6 +1,6 @@
 import numpy as np
 
-from matplotlib import _api, cbook
+from matplotlib import _api
 from matplotlib.collections import PolyCollection, TriMesh
 from matplotlib.colors import Normalize
 from matplotlib.tri.triangulation import Triangulation
@@ -114,7 +114,7 @@ def tripcolor(ax, *args, alpha=1.0, norm=None, cmap=None, vmin=None,
 
     collection.set_alpha(alpha)
     collection.set_array(C)
-    cbook._check_isinstance((Normalize, None), norm=norm)
+    _api.check_isinstance((Normalize, None), norm=norm)
     collection.set_cmap(cmap)
     collection.set_norm(norm)
     collection._scale_norm(norm, vmin, vmax)
diff --git a/lib/matplotlib/tri/trirefine.py b/lib/matplotlib/tri/trirefine.py
index b253dbaaca8e..7ba66d0ea5c6 100644
--- a/lib/matplotlib/tri/trirefine.py
+++ b/lib/matplotlib/tri/trirefine.py
@@ -4,7 +4,7 @@
 
 import numpy as np
 
-from matplotlib import cbook
+from matplotlib import _api
 from matplotlib.tri.triangulation import Triangulation
 import matplotlib.tri.triinterpolate
 
@@ -40,7 +40,7 @@ class TriRefiner:
     """
 
     def __init__(self, triangulation):
-        cbook._check_isinstance(Triangulation, triangulation=triangulation)
+        _api.check_isinstance(Triangulation, triangulation=triangulation)
         self._triangulation = triangulation
 
 
@@ -158,8 +158,8 @@ def refine_field(self, z, triinterpolator=None, subdiv=3):
             interp = matplotlib.tri.CubicTriInterpolator(
                 self._triangulation, z)
         else:
-            cbook._check_isinstance(matplotlib.tri.TriInterpolator,
-                                    triinterpolator=triinterpolator)
+            _api.check_isinstance(matplotlib.tri.TriInterpolator,
+                                  triinterpolator=triinterpolator)
             interp = triinterpolator
 
         refi_tri, found_index = self.refine_triangulation(
diff --git a/lib/matplotlib/tri/tritools.py b/lib/matplotlib/tri/tritools.py
index 90a9db8461a5..bda8f7c0248f 100644
--- a/lib/matplotlib/tri/tritools.py
+++ b/lib/matplotlib/tri/tritools.py
@@ -4,7 +4,7 @@
 
 import numpy as np
 
-from matplotlib import cbook
+from matplotlib import _api
 from matplotlib.tri import Triangulation
 
 
@@ -26,7 +26,7 @@ class TriAnalyzer:
     """
 
     def __init__(self, triangulation):
-        cbook._check_isinstance(Triangulation, triangulation=triangulation)
+        _api.check_isinstance(Triangulation, triangulation=triangulation)
         self._triangulation = triangulation
 
     @property
diff --git a/lib/mpl_toolkits/axes_grid1/axes_size.py b/lib/mpl_toolkits/axes_grid1/axes_size.py
index 541ec7f64959..87bc2419e1b4 100644
--- a/lib/mpl_toolkits/axes_grid1/axes_size.py
+++ b/lib/mpl_toolkits/axes_grid1/axes_size.py
@@ -11,7 +11,7 @@ class (or others) to determine the size of each axes. The unit
 
 from numbers import Number
 
-from matplotlib import _api, cbook
+from matplotlib import _api
 from matplotlib.axes import Axes
 
 
@@ -54,7 +54,7 @@ class Fixed(_Base):
     """
 
     def __init__(self, fixed_size):
-        cbook._check_isinstance(Number, fixed_size=fixed_size)
+        _api.check_isinstance(Number, fixed_size=fixed_size)
         self.fixed_size = fixed_size
 
     def get_size(self, renderer):
@@ -189,7 +189,7 @@ class Fraction(_Base):
     """
 
     def __init__(self, fraction, ref_size):
-        cbook._check_isinstance(Number, fraction=fraction)
+        _api.check_isinstance(Number, fraction=fraction)
         self._fraction_ref = ref_size
         self._fraction = fraction