I've been watching Marvel's Agent Carter, and I've noticed that almost every male character wearing a tie wears it well above his bellybutton. I have always been told that the end of my tie should be around or just above my belt, so I was curious if it was in fashion in the mid-late 1940's to wear ties fairly short compared to how ties are worn now.
It's more that waistcoats were still worn as part of a suit, and ties didn't need to be long, since the low end of the tie is hidden behind the waistcoat.
In the 1930s, the waistcoat wasn't worn as often, and in summer, men often wore only a lightweight, two piece suit instead.
Edit: struggling to find a good source to support this (bar contemporary pictures), so calling flaired users who are into Western fashion:
/u/cecikierk, /u/jerisad
You actually caught on to the answer when you mentioned that your tie should end just above your pants. The difference now is that your pants are worn well below the waist, whereas in the 1940s pants were often at or even slightly above the natural waist (which is normally above the belly button). The general proportions of ties in the late 1940s were fairly wide and look stubby in comparison with the narrow tie that has been in fashion lately. Some images do show their ties a little shorter, but it's difficult to say if it was a fashion choice or simply poor tying on their part (or the tie may be planned for under a vest). This website is a good place to see an overview of mens 1940s fashion.