diff -r 15f82b64eee0 Lib/calendar.py
--- a/Lib/calendar.py	Thu Sep 22 17:11:53 2016 -0700
+++ b/Lib/calendar.py	Fri Sep 23 16:01:52 2016 +0800
@@ -366,7 +366,7 @@
                         weeks.append('')
                     else:
                         weeks.append(self.formatweek(cal[j], w))
-                a(formatstring(weeks, colwidth, c).rstrip())
+                a(formatstring1(weeks, colwidth, c).rstrip())
                 a('\n' * l)
         return ''.join(v)
 
@@ -591,6 +591,9 @@
     spacing *= ' '
     return spacing.join(c.center(colwidth) for c in cols)
 
+def formatstring1(cols, colwidth=_colwidth, spacing=_spacing):
+    spacing *= ' '
+    return spacing.join(c.ljust(colwidth) for c in cols)
 
 EPOCH = 1970
 _EPOCH_ORD = datetime.date(EPOCH, 1, 1).toordinal()
diff -r 15f82b64eee0 Lib/test/test_calendar.py
--- a/Lib/test/test_calendar.py	Thu Sep 22 17:11:53 2016 -0700
+++ b/Lib/test/test_calendar.py	Fri Sep 23 16:01:52 2016 +0800
@@ -311,6 +311,43 @@
        '12/20/04 12/21/04 12/22/04 12/23/04 12/24/04 12/25/04 12/26/04',
        '12/27/04 12/28/04 12/29/04 12/30/04 12/31/04 01/01/05 01/02/05']]]
 
+result_9999_text = """
+                                  9999
+
+      January                   February                   March
+Mo Tu We Th Fr Sa Su      Mo Tu We Th Fr Sa Su      Mo Tu We Th Fr Sa Su
+             1  2  3       1  2  3  4  5  6  7       1  2  3  4  5  6  7
+ 4  5  6  7  8  9 10       8  9 10 11 12 13 14       8  9 10 11 12 13 14
+11 12 13 14 15 16 17      15 16 17 18 19 20 21      15 16 17 18 19 20 21
+18 19 20 21 22 23 24      22 23 24 25 26 27 28      22 23 24 25 26 27 28
+25 26 27 28 29 30 31                                29 30 31
+
+       April                      May                       June
+Mo Tu We Th Fr Sa Su      Mo Tu We Th Fr Sa Su      Mo Tu We Th Fr Sa Su
+          1  2  3  4                      1  2          1  2  3  4  5  6
+ 5  6  7  8  9 10 11       3  4  5  6  7  8  9       7  8  9 10 11 12 13
+12 13 14 15 16 17 18      10 11 12 13 14 15 16      14 15 16 17 18 19 20
+19 20 21 22 23 24 25      17 18 19 20 21 22 23      21 22 23 24 25 26 27
+26 27 28 29 30            24 25 26 27 28 29 30      28 29 30
+                          31
+
+        July                     August                  September
+Mo Tu We Th Fr Sa Su      Mo Tu We Th Fr Sa Su      Mo Tu We Th Fr Sa Su
+          1  2  3  4                         1             1  2  3  4  5
+ 5  6  7  8  9 10 11       2  3  4  5  6  7  8       6  7  8  9 10 11 12
+12 13 14 15 16 17 18       9 10 11 12 13 14 15      13 14 15 16 17 18 19
+19 20 21 22 23 24 25      16 17 18 19 20 21 22      20 21 22 23 24 25 26
+26 27 28 29 30 31         23 24 25 26 27 28 29      27 28 29 30
+                          30 31
+
+      October                   November                  December
+Mo Tu We Th Fr Sa Su      Mo Tu We Th Fr Sa Su      Mo Tu We Th Fr Sa Su
+             1  2  3       1  2  3  4  5  6  7             1  2  3  4  5
+ 4  5  6  7  8  9 10       8  9 10 11 12 13 14       6  7  8  9 10 11 12
+11 12 13 14 15 16 17      15 16 17 18 19 20 21      13 14 15 16 17 18 19
+18 19 20 21 22 23 24      22 23 24 25 26 27 28      20 21 22 23 24 25 26
+25 26 27 28 29 30 31      29 30                     27 28 29 30 31
+"""
 
 class OutputTestCase(unittest.TestCase):
     def normalize_calendar(self, s):
@@ -417,6 +454,12 @@
             calendar.TextCalendar().pryear(2004)
             self.assertEqual(out.getvalue().strip(), result_2004_text.strip())
 
+    def test_pryear_9999(self):
+        # issue 28253
+        with support.captured_stdout() as out:
+            calendar.TextCalendar().pryear(9999)
+            self.assertEqual(out.getvalue().strip(), result_9999_text.strip())
+
     def test_format(self):
         with support.captured_stdout() as out:
             calendar.format(["1", "2", "3"], colwidth=3, spacing=1)
@@ -820,7 +863,8 @@
         blacklist = {'mdays', 'January', 'February', 'EPOCH',
                      'MONDAY', 'TUESDAY', 'WEDNESDAY', 'THURSDAY', 'FRIDAY',
                      'SATURDAY', 'SUNDAY', 'different_locale', 'c',
-                     'prweek', 'week', 'format', 'formatstring', 'main'}
+                     'prweek', 'week', 'format', 'formatstring', 'formatstring1',
+                     'main'}
         support.check__all__(self, calendar, blacklist=blacklist)