diff --git a/INSTALL b/INSTALL
index 1862b3a6e..31b7ab955 100644
--- a/INSTALL
+++ b/INSTALL
@@ -73,7 +73,7 @@ The recipes for these can be found at https://github.com/conda-forge/feedstocks.
 **pyshp** 1.1.4 or later (https://pypi.python.org/pypi/pyshp)
     Pure Python read/write support for ESRI Shapefile format.
 
-**PROJ.4** 4.9.0 or later (http://proj4.org/)
+**PROJ** 4.9.0 or later (https://proj4.org/)
     Cartographic Projections library.
 
 **six** 1.3.0 or later (https://pypi.python.org/pypi/six)
diff --git a/lib/cartopy/_crs.pxd b/lib/cartopy/_crs.pxd
index fab9ab427..d377b5702 100644
--- a/lib/cartopy/_crs.pxd
+++ b/lib/cartopy/_crs.pxd
@@ -22,7 +22,7 @@ cdef extern from "proj_api.h":
 
 cdef class CRS:
     """
-    Defines a Coordinate Reference System using proj.4.
+    Defines a Coordinate Reference System using proj.
 
     """
 
diff --git a/lib/cartopy/_crs.pyx b/lib/cartopy/_crs.pyx
index 1def57c6b..650750578 100644
--- a/lib/cartopy/_crs.pyx
+++ b/lib/cartopy/_crs.pyx
@@ -16,7 +16,7 @@
 # along with cartopy.  If not, see <https://www.gnu.org/licenses/>.
 
 """
-This module defines the core CRS class which can interface with Proj.4.
+This module defines the core CRS class which can interface with Proj.
 The CRS class is the base-class for all projections defined in :mod:`cartopy.crs`.
 
 """
@@ -70,7 +70,7 @@ class Proj4Error(Exception):
     def __init__(self):
         cdef int status
         status = deref(pj_get_errno_ref())
-        msg = 'Error from proj.4: {}'.format(pj_strerrno(status))
+        msg = 'Error from proj: {}'.format(pj_strerrno(status))
         self.status = status
         Exception.__init__(self, msg)
 
@@ -88,9 +88,9 @@ class Globe(object):
         Parameters
         ----------
         datum
-            Proj4 "datum" definition. Defaults to None.
+            Proj "datum" definition. Defaults to None.
         ellipse
-            Proj4 "ellps" definition. Defaults to 'WGS84'.
+            Proj "ellps" definition. Defaults to 'WGS84'.
         semimajor_axis
             Semimajor axis of the spheroid / ellipsoid.  Defaults to None.
         semiminor_axis
@@ -100,9 +100,9 @@ class Globe(object):
         inverse_flattening
             Inverse flattening of the ellipsoid.  Defaults to None.
         towgs84
-            Passed through to the Proj4 definition.  Defaults to None.
+            Passed through to the Proj definition.  Defaults to None.
         nadgrids
-            Passed through to the Proj4 definition.  Defaults to None.
+            Passed through to the Proj definition.  Defaults to None.
 
         """
         self.datum = datum
@@ -117,7 +117,7 @@ class Globe(object):
     def to_proj4_params(self):
         """
         Create an OrderedDict of key value pairs which represents this globe
-        in terms of proj4 params.
+        in terms of proj params.
 
         """
         proj4_params = (['datum', self.datum], ['ellps', self.ellipse],
@@ -129,7 +129,7 @@ class Globe(object):
 
 cdef class CRS:
     """
-    Define a Coordinate Reference System using proj.4.
+    Define a Coordinate Reference System using proj.
 
     """
     def __cinit__(self):
@@ -276,8 +276,8 @@ cdef class CRS:
             instance of :class:`CRS` that represents the coordinate
             system of ``x`` and ``y``.
         trap
-            Whether proj.4 errors for "latitude or longitude exceeded
-            limits" and "tolerance condition error" should be trapped.
+            Whether proj errors for "latitude or longitude exceeded limits" and
+            "tolerance condition error" should be trapped.
 
         Returns
         -------
@@ -376,7 +376,7 @@ cdef class CRS:
         else:
             result[:, 2] = z
 
-        # call proj.4. The result array is modified in place. This is only
+        # call proj. The result array is modified in place. This is only
         # safe if npts is not 0.
         if npts:
             status = pj_transform(src_crs.proj4, self.proj4, npts, 3,
diff --git a/lib/cartopy/crs.py b/lib/cartopy/crs.py
index f903438bd..153adad41 100644
--- a/lib/cartopy/crs.py
+++ b/lib/cartopy/crs.py
@@ -52,7 +52,7 @@ class RotatedGeodetic(CRS):
 
     Coordinates are measured in degrees.
 
-    The class uses proj4 to perform an ob_tran operation, using the
+    The class uses proj to perform an ob_tran operation, using the
     pole_longitude to set a lon_0 then performing two rotations based on
     pole_latitude and central_rotated_longitude.
     This is equivalent to setting the new pole to a location defined by
@@ -994,7 +994,7 @@ def __init__(self, central_longitude=0.0,
 
         super(Mercator, self).__init__(proj4_params, globe=globe)
 
-        # In new proj.4, using exact limits will wrap-around, so subtract a
+        # In new proj, using exact limits will wrap-around, so subtract a
         # small epsilon:
         epsilon = 1e-10
         minlon = -180 + central_longitude
@@ -1276,7 +1276,7 @@ def __init__(self, central_longitude=0.0, globe=None):
         b = np.float(globe.semiminor_axis or a)
 
         if b != a or globe.ellipse is not None:
-            warnings.warn('The proj4 "mill" projection does not handle '
+            warnings.warn('The proj "mill" projection does not handle '
                           'elliptical globes.')
 
         proj4_params = [('proj', 'mill'), ('lon_0', central_longitude)]
@@ -1298,7 +1298,7 @@ class RotatedPole(_CylindricalProjection):
 
     Coordinates are measured in projection metres.
 
-    The class uses proj4 to perform an ob_tran operation, using the
+    The class uses proj to perform an ob_tran operation, using the
     pole_longitude to set a lon_0 then performing two rotations based on
     pole_latitude and central_rotated_longitude.
     This is equivalent to setting the new pole to a location defined by
@@ -1367,20 +1367,20 @@ def __init__(self, central_latitude=0.0, central_longitude=0.0,
                  false_easting=0.0, false_northing=0.0,
                  true_scale_latitude=None,
                  scale_factor=None, globe=None):
-        # Warn when using Stereographic with proj4 < 5.0.0 due to
+        # Warn when using Stereographic with proj < 5.0.0 due to
         # incorrect transformation with lon_0=0 (see
         # https://github.com/OSGeo/proj.4/issues/194).
         if central_latitude == 0:
             if PROJ4_VERSION != ():
                 if PROJ4_VERSION < (5, 0, 0):
                     warnings.warn(
-                        'The Stereographic projection in Proj.4 older than '
+                        'The Stereographic projection in Proj older than '
                         '5.0.0 incorrectly transforms points when '
                         'central_latitude=0. Use this projection with '
                         'caution.')
             else:
                 warnings.warn(
-                    'Cannot determine Proj.4 version. The Stereographic '
+                    'Cannot determine Proj version. The Stereographic '
                     'projection may be unreliable and should be used with '
                     'caution.')
 
@@ -1476,7 +1476,7 @@ def __init__(self, central_longitude=0.0, central_latitude=0.0,
         b = np.float(self.globe.semiminor_axis or a)
 
         if b != a:
-            warnings.warn('The proj4 "ortho" projection does not appear to '
+            warnings.warn('The proj "ortho" projection does not appear to '
                           'handle elliptical globes.')
 
         # To stabilise the projection of geometries, we reduce the boundary by
@@ -1509,7 +1509,7 @@ def __init__(self, proj4_params, central_longitude, globe=None):
         super(_WarpedRectangularProjection, self).__init__(proj4_params,
                                                            globe=globe)
 
-        # In new proj.4, using exact limits will wrap-around, so subtract a
+        # In new proj, using exact limits will wrap-around, so subtract a
         # small epsilon:
         epsilon = 1.e-10
         minlon = -180 + central_longitude
@@ -1562,17 +1562,17 @@ def threshold(self):
 
 class Robinson(_WarpedRectangularProjection):
     def __init__(self, central_longitude=0, globe=None):
-        # Warn when using Robinson with proj4 4.8 due to discontinuity at
+        # Warn when using Robinson with proj 4.8 due to discontinuity at
         # 40 deg N introduced by incomplete fix to issue #113 (see
         # https://github.com/OSGeo/proj.4/issues/113).
         if PROJ4_VERSION != ():
             if (4, 8) <= PROJ4_VERSION < (4, 9):
                 warnings.warn('The Robinson projection in the v4.8.x series '
-                              'of Proj.4 contains a discontinuity at '
+                              'of Proj contains a discontinuity at '
                               '40 deg latitude. Use this projection with '
                               'caution.')
         else:
-            warnings.warn('Cannot determine Proj.4 version. The Robinson '
+            warnings.warn('Cannot determine Proj version. The Robinson '
                           'projection may be unreliable and should be used '
                           'with caution.')
 
@@ -1905,17 +1905,17 @@ def __init__(self, central_longitude=0.0, central_latitude=0.0,
             globe is created.
 
         """
-        # Warn when using Azimuthal Equidistant with proj4 < 4.9.2 due to
+        # Warn when using Azimuthal Equidistant with proj < 4.9.2 due to
         # incorrect transformation past 90 deg distance (see
         # https://github.com/OSGeo/proj.4/issues/246).
         if PROJ4_VERSION != ():
             if PROJ4_VERSION < (4, 9, 2):
-                warnings.warn('The Azimuthal Equidistant projection in Proj.4 '
+                warnings.warn('The Azimuthal Equidistant projection in Proj '
                               'older than 4.9.2 incorrectly transforms points '
                               'farther than 90 deg from the origin. Use this '
                               'projection with caution.')
         else:
-            warnings.warn('Cannot determine Proj.4 version. The Azimuthal '
+            warnings.warn('Cannot determine Proj version. The Azimuthal '
                           'Equidistant projection may be unreliable and '
                           'should be used with caution.')
 
diff --git a/lib/cartopy/geodesic/_geodesic.pyx b/lib/cartopy/geodesic/_geodesic.pyx
index 05114238c..f9dcb0824 100644
--- a/lib/cartopy/geodesic/_geodesic.pyx
+++ b/lib/cartopy/geodesic/_geodesic.pyx
@@ -16,7 +16,7 @@
 # along with cartopy.  If not, see <https://www.gnu.org/licenses/>.
 
 """
-This module defines the Geodesic class which can interface with the Proj.4.
+This module defines the Geodesic class which can interface with the Proj
 geodesic functions.
 
 """
diff --git a/lib/cartopy/tests/crs/test_robinson.py b/lib/cartopy/tests/crs/test_robinson.py
index ecf65cf83..891bf0e7d 100644
--- a/lib/cartopy/tests/crs/test_robinson.py
+++ b/lib/cartopy/tests/crs/test_robinson.py
@@ -1,4 +1,4 @@
-# (C) British Crown Copyright 2013 - 2017, Met Office
+# (C) British Crown Copyright 2013 - 2018, Met Office
 #
 # This file is part of cartopy.
 #
@@ -35,7 +35,7 @@
 _CRS_PC = ccrs.PlateCarree()
 _CRS_ROB = ccrs.Robinson()
 
-# Increase tolerance if using older proj.4 releases
+# Increase tolerance if using older proj releases
 _TOL = -1 if ccrs.PROJ4_VERSION < (4, 9) else 7
 
 
diff --git a/lib/cartopy/tests/crs/test_stereographic.py b/lib/cartopy/tests/crs/test_stereographic.py
index 3bfd49781..339491e05 100644
--- a/lib/cartopy/tests/crs/test_stereographic.py
+++ b/lib/cartopy/tests/crs/test_stereographic.py
@@ -60,7 +60,7 @@ def test_eccentric_globe(self):
     def test_true_scale(self):
         # The "true_scale_latitude" parameter only makes sense for
         # polar stereographic projections (#339 and #455).
-        # For now only the proj4 string creation is tested
+        # For now only the proj string creation is tested
         # See test_scale_factor for test on projection.
         globe = ccrs.Globe(ellipse='sphere')
         stereo = ccrs.NorthPolarStereo(true_scale_latitude=30, globe=globe)
diff --git a/lib/cartopy/tests/mpl/test_mpl_integration.py b/lib/cartopy/tests/mpl/test_mpl_integration.py
index b852e19a3..16d150fb5 100644
--- a/lib/cartopy/tests/mpl/test_mpl_integration.py
+++ b/lib/cartopy/tests/mpl/test_mpl_integration.py
@@ -172,9 +172,9 @@ def test_multiple_projections():
                    ]
 
     if ccrs.PROJ4_VERSION < (5, 0, 0):
-        # Produce the same sized image for old proj4, to avoid having to
-        # replace the image. If this figure is regenerated for both old and new
-        # proj4, then drop this condition.
+        # Produce the same sized image for old proj, to avoid having to replace
+        # the image. If this figure is regenerated for both old and new proj,
+        # then drop this condition.
         rows = 5
     else:
         rows = np.ceil(len(projections) / 5)
diff --git a/lib/cartopy/tests/test_crs.py b/lib/cartopy/tests/test_crs.py
index 719c2be37..d03373601 100644
--- a/lib/cartopy/tests/test_crs.py
+++ b/lib/cartopy/tests/test_crs.py
@@ -118,7 +118,7 @@ def test_transform_points_nD(self):
         unrotated_lon = res[..., 0]
         unrotated_lat = res[..., 1]
 
-        # Solutions derived by proj4 direct.
+        # Solutions derived by proj direct.
         solx = np.array([[-16.42176094, -14.85892262, -11.90627520],
                          [-16.71055023, -14.58434624, -11.68799988]])
         soly = np.array([[46.00724251, 51.29188893, 52.59101488],
@@ -138,7 +138,7 @@ def test_transform_points_1D(self):
         unrotated_lon = res[..., 0]
         unrotated_lat = res[..., 1]
 
-        # Solutions derived by proj4 direct.
+        # Solutions derived by proj direct.
         solx = np.array([-16.42176094, -14.85892262,
                          -12.88946157, -10.35078336])
         soly = np.array([46.00724251, 51.29188893,
diff --git a/lib/cartopy/trace.pyx b/lib/cartopy/trace.pyx
index 77726201a..f2f352040 100644
--- a/lib/cartopy/trace.pyx
+++ b/lib/cartopy/trace.pyx
@@ -16,10 +16,10 @@
 # along with cartopy.  If not, see <https://www.gnu.org/licenses/>.
 
 """
-This module pulls together _trace.cpp, proj.4, GEOS and _crs.pyx to implement a function
-to project a LinearRing/LineString. In general, this should never be called manually,
-instead leaving the processing to be done by the :class:`cartopy.crs.Projection`
-subclasses.
+This module pulls together _trace.cpp, proj, GEOS and _crs.pyx to implement a
+function to project a LinearRing/LineString. In general, this should never be
+called manually, instead leaving the processing to be done by the
+:class:`cartopy.crs.Projection` subclasses.
 """
 
 from libc.stdint cimport uintptr_t as ptr
diff --git a/setup.py b/setup.py
index 6e67d1daf..b0409ac6f 100644
--- a/setup.py
+++ b/setup.py
@@ -205,19 +205,19 @@ def _header_bad(self, path):
             geos_libraries.append(entry[2:])
 
 
-# Proj4
+# Proj
 def find_proj_version_by_program(conda=None):
     proj = find_executable('proj')
     if proj is None:
         print(
-            'Proj4 %s must be installed.' % (
+            'Proj %s must be installed.' % (
                 '.'.join(str(v) for v in PROJ_MIN_VERSION), ),
             file=sys.stderr)
         exit(1)
 
     if conda is not None and conda not in proj:
         print(
-            'Proj4 %s must be installed in Conda environment "%s".' % (
+            'Proj %s must be installed in Conda environment "%s".' % (
                 '.'.join(str(v) for v in PROJ_MIN_VERSION), conda),
             file=sys.stderr)
         exit(1)
@@ -229,7 +229,7 @@ def find_proj_version_by_program(conda=None):
         proj_version = tuple(int(v.strip(b',')) for v in proj_version)
     except (OSError, IndexError, ValueError, subprocess.CalledProcessError):
         warnings.warn(
-            'Unable to determine Proj4 version. Ensure you have %s or later '
+            'Unable to determine Proj version. Ensure you have %s or later '
             'installed, or installation may fail.' % (
                 '.'.join(str(v) for v in PROJ_MIN_VERSION), ))
         proj_version = (0, 0, 0)
@@ -245,7 +245,7 @@ def find_proj_version_by_program(conda=None):
     proj_version = find_proj_version_by_program(conda)
     if proj_version < PROJ_MIN_VERSION:
         print(
-            'Proj4 version %s is installed, but cartopy requires at least '
+            'Proj version %s is installed, but cartopy requires at least '
             'version %s.' % ('.'.join(str(v) for v in proj_version),
                              '.'.join(str(v) for v in PROJ_MIN_VERSION)),
             file=sys.stderr)
@@ -268,7 +268,7 @@ def find_proj_version_by_program(conda=None):
         proj_version = find_proj_version_by_program()
         if proj_version < PROJ_MIN_VERSION:
             print(
-                'Proj4 version %s is installed, but cartopy requires at least '
+                'Proj version %s is installed, but cartopy requires at least '
                 'version %s.' % ('.'.join(str(v) for v in proj_version),
                                  '.'.join(str(v) for v in PROJ_MIN_VERSION)),
                 file=sys.stderr)
@@ -280,7 +280,7 @@ def find_proj_version_by_program(conda=None):
     else:
         if proj_version < PROJ_MIN_VERSION:
             print(
-                'Proj4 version %s is installed, but cartopy requires at least '
+                'Proj version %s is installed, but cartopy requires at least '
                 'version %s.' % ('.'.join(str(v) for v in proj_version),
                                  '.'.join(str(v) for v in PROJ_MIN_VERSION)),
                 file=sys.stderr)
@@ -353,7 +353,7 @@ def get_config_var(name):
     long_description=description,
     long_description_content_type='text/markdown',
     license="LGPLv3",
-    keywords="cartography map transform projection proj.4 geos shapely "
+    keywords="cartography map transform projection proj proj.4 geos shapely "
              "shapefile",
 
     install_requires=install_requires,
@@ -377,7 +377,7 @@ def get_config_var(name):
                   ['io/srtm.npz']},
 
 
-    # requires proj4 headers
+    # requires proj headers
     ext_modules=[
         Extension(
             'cartopy.trace',
@@ -397,7 +397,7 @@ def get_config_var(name):
             library_dirs=[library_dir] + proj_library_dirs,
             **extra_extension_args
         ),
-        # Requires proj4 v4.9
+        # Requires proj v4.9
         Extension(
             'cartopy.geodesic._geodesic',
             ['lib/cartopy/geodesic/_geodesic.pyx'],