diff --git a/lib/area/string.rb b/lib/area/string.rb
index 5a7fe90..1f6fdd9 100644
--- a/lib/area/string.rb
+++ b/lib/area/string.rb
@@ -27,12 +27,14 @@ def to_area
   #
   # Returns a String of converted area codes or zipcodes.
   def to_region(options = {})
-    if self.to_s.length == 3  # an area code
-      row = Area.area_codes.find {|row| row.first == self.to_s }
+    code = self.to_s
+    code = code[0..4] if code.match(/^\d{5}-?\d{4}$/)
+    if code.length == 3  # an area code
+      row = Area.area_codes.find {|row| row.first == code }
       return row.last if row
-    elsif self.to_s.length == 5
-      if row = Area.zip_codes.find {|row| row.first == self.to_s }
-        if row.first == self.to_s
+    elsif code.length == 5
+      if row = Area.zip_codes.find {|row| row.first == code }
+        if row.first == code
           if options[:city]
             return row[1]
           elsif options[:state]
diff --git a/test/unit/area_test.rb b/test/unit/area_test.rb
index 6173932..67c571d 100644
--- a/test/unit/area_test.rb
+++ b/test/unit/area_test.rb
@@ -63,6 +63,13 @@ def test_that_it_converts_zip_code_to_region
     assert_equal "Brooklyn, NY", "11211".to_region
   end
 
+  def test_that_it_supports_nine_digits_for_zipcodes
+    assert_equal "Brooklyn, NY", "11211-1111".to_region
+    assert_equal "Brooklyn, NY", "112111111".to_region
+    assert_equal "Brooklyn", "11211-1111".to_region(:city => true)
+    assert_equal "NY", "11211-1111".to_region(:state => true)
+  end
+
   def test_that_it_supports_options_for_zipcodes
     assert_equal "Brooklyn", "11211".to_region(:city => true)
     assert_equal "NY", "11211".to_region(:state => true)
@@ -101,6 +108,9 @@ def test_that_it_returns_false_for_daylight_savings_time_nonobservance
   def test_that_it_handles_incorrect_zips
     assert_equal [], "9888".to_zip
     assert_raises(ArgumentError) { "9888".to_region }
+    assert_raises(ArgumentError) { "988888".to_region }
+    assert_raises(ArgumentError) { "98888-44444".to_region }
+    assert_raises(ArgumentError) { "9888844444".to_region }
     assert_raises(ArgumentError) { "9888".to_area }
     assert_raises(ArgumentError) { "9888".to_gmt_offset }
     assert_raises(ArgumentError) { "9888".to_dst }