When did the transition from standard definition (4:3) to widescreen (16:9) for television anime happen? Modern television anime is produced at an aspect ratio of 16:9 - widescreen/HD. But in the past, television anime was more often produced at an aspect ratio of 4:3 - standard definition.

When did the transition from 4:3 to 16:9 for television anime happen?

Now, it's not too difficult to find isolated examples to get a sense for when the switchover was in progress. For example, Ouran High School Host Club, from spring 2006, was produced at 4:3, while Full Metal Panic! The Second Raid, from summer 2005, was produced at 16:9. Clearly, the transition was under way by 2005, but not complete by 2006. And I'm fairly confident that by 2011, all television anime were in 16:9 (Ninja Slayer notwithstanding). 

But what I'm looking for is a more holistic view of how this transition happened. Who were the major players? Can we identify a clear starting date for the transition? And so forth.
According to user Zalis on the MyAnimeList forums, one of the first instances of widescreen anime was Betterman (1999). However, because it isn't one of the better known shows, it often gets overlooked and Vandread (2000) is often accredited with the first.

The cinema is often the first place for the widescreen transition of visual media, and early animated (and non-animated) films were sometimes shown in widescsreen at the cinema, and later reshaped for broadcast/dvd. The earliest example I could find for this was Magic Boy (1960~) This was  2.40:1 rather than 16:9 though. You can see the difference between the aspect ratios below:



I don't think there are any specific points in time that we can point to where there was a definite switch - just as the transition to digital happened, but the full transition seems to be almost done in 2006-2008, when 4:3 anime became minimal and even the larger series like One Piece, Naruto, etc switched over.

References: 


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