Both "den ganzen Tag" and "den ganzen Tag über" means "all day". Is there any difference in connotation? Is it perhaps that "den ganzen Tag über" gives an impression similar to "all day long", i.e., makes it clear that it is indeed the whole day?
Example from the Frankfurter Allgemeine:
Es war die Nacht der großen Gefühle. Den ganzen Tag über waren die Menschen in feierlichen Zügen zu den Urnen geströmt, ...
(A similar question holds for "den ganzen Abend über", etc.)