diff --git a/ci/doc_requirements.txt b/ci/doc_requirements.txt
index 2b02c00e9..9a434aa52 100644
--- a/ci/doc_requirements.txt
+++ b/ci/doc_requirements.txt
@@ -1,8 +1,8 @@
 cartopy==0.24
 matplotlib==3.9.2
 metpy==1.6.3
-sphinx==5.2.3
-sphinx_rtd_theme==1.0.0
+sphinx==8.1.3
+sphinx_rtd_theme==3.0.1
 sphinx-gallery==0.18.0
-myst-parser==0.18.1
+myst-parser==4.0.0
 netCDF4==1.7.2
diff --git a/docs/conf.py b/docs/conf.py
index 1c772726c..4c119396f 100644
--- a/docs/conf.py
+++ b/docs/conf.py
@@ -137,23 +137,12 @@
 
 # The theme to use for HTML and HTML Help pages.  See the documentation for
 # a list of builtin themes.
-#html_theme = 'default'
-try:
-    import sphinx_rtd_theme
-    html_theme = 'sphinx_rtd_theme'
-    html_theme_path = [sphinx_rtd_theme.get_html_theme_path()]
-except ImportError:
-    pass
-
-def setup(app):
-        app.add_css_file('theme_override.css')
+html_theme = 'sphinx_rtd_theme'
 
 # Theme options are theme-specific and customize the look and feel of a theme
 # further.  For a list of options available for each theme, see the
 # documentation.
 html_theme_options = {'canonical_url': 'https://unidata.github.io/siphon/latest/'}
-if 'sphinx_rtd_theme' in vars() and sphinx_rtd_theme.__version__ == '0.2.5b1.post1':
-    html_theme_options['versions'] = {'latest': '../latest', 'dev': '../dev'}
 
 # Extra variables that will be available to the templates. Used to create the
 # links to the Github repository sources and issues
@@ -186,6 +175,7 @@ def setup(app):
 # relative to this directory. They are copied after the builtin static files,
 # so a file named "default.css" will overwrite the builtin "default.css".
 html_static_path = ['_static']
+html_css_files = ['theme_override.css']
 
 # Add any extra paths that contain custom files (such as robots.txt or
 # .htaccess) here, relative to this directory. These files are copied
diff --git a/examples/acis/Mapping_Example.py b/examples/acis/Mapping_Example.py
index b1b3e2b69..e0e196d03 100644
--- a/examples/acis/Mapping_Example.py
+++ b/examples/acis/Mapping_Example.py
@@ -122,15 +122,11 @@
 fig = plt.figure(figsize=(20, 10))
 ax = fig.add_subplot(1, 1, 1, projection=proj)
 
-state_boundaries = feat.NaturalEarthFeature(category='cultural',
-                                            name='admin_1_states_provinces_lines',
-                                            scale='110m', facecolor='none')
-
 ax.add_feature(feat.LAND, zorder=-1)
 ax.add_feature(feat.OCEAN, zorder=-1)
 ax.add_feature(feat.LAKES, zorder=-1)
 ax.coastlines(resolution='110m', zorder=2, color='black')
-ax.add_feature(state_boundaries, edgecolor='black')
+ax.add_feature(feat.STATES, edgecolor='black')
 ax.add_feature(feat.BORDERS, linewidth=2, edgecolor='black')
 
 # Set plot bounds