Difference between “den ganzen Tag” and “den ganzen Tag über”?

Question

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.)

Answer 1

It's one of the basic functions of über, meaning lang or während. For me there's no difference in meaning. Maybe the variant without über is even a contraction of the one with it. Additionally, here's a drawing:

Fits, doesn't it? Apart from this intuitive approach, I can't find any other (e.g. etymological) "reasons" for über in this context.

Answer 2

There is really not much of a difference, I think. Perhaps den ganzen Tag über could be translated as all day long.