--- a/tests/test_grid.py	Sat Jun 24 14:48:55 2017 -0700
+++ b/tests/test_grid.py	Sat Jun 24 15:16:10 2017 -0700
@@ -9,6 +9,7 @@
 from common import datafile
 from globalneighbors.grid import LatLonGrid
 from globalneighbors.locations import locations
+from globalneighbors.read import read_cities
 from globalneighbors.read import read_city_list
 
 
@@ -44,6 +45,16 @@
         city_locations = locations(read_city_list(samplefile))
         self.grid_locations(city_locations)
 
+    def test_10000(self):
+        """test 10000 cities"""
+
+        filename = datafile('10000cities.tsv')
+        assert os.path.exists(filename)
+        with open(filename) as f:
+            city_locations = locations(read_cities(f))
+        self.grid_locations(city_locations)
+
+
     ### generic (utility) functions
 
     def grid_locations(self, locations):
@@ -63,5 +74,7 @@
                 n_locations += len(grid[(i,j)])
         assert n_locations == len(locations)
 
+
+
 if __name__ == '__main__':
     unittest.main()