> > (classic NTSC has always been 720i)
>
> No it hasn't.  It's 486 visible lines, of which a few often get lost off
> the top or bottom; most people round off as 480 lines and 640 columns
> actual viewable area.

You're measuring the height. The width is 720. When transcoded for a computer,
it is often scaled to 640x480 for square pixels.