You don't want a maximally "efficient" vacancy rate (i.e. 0), because that makes it basically impossible for people to move around - and that gives enormous power to landlords to gouge tenants.
So what vacancy rate do you want, ideally? Not sure, but you'll notice from your own source that 6.9% is around as low a vacancy rate as the US has had since the turn of the millennium.
FWIW, looking at vacancy statistics across the whole of the country can be misleading. They include houses that are vacant for any reason - including properties that are condemned, under renovation, or in the middle of nowhere where there are no jobs.
That latter point is key. As more and more economic activity has moved to white-collar coastal cities and away from rural or suburban blue-collar middle America, it's no surprise there are going to be vacancies in regions where the economy's been hollowed out. So we can conjecture that the record low vacancy rate is even more problematic, because those vacancies are likely less equally distributed to areas that need them.
So what vacancy rate do you want, ideally? Not sure, but you'll notice from your own source that 6.9% is around as low a vacancy rate as the US has had since the turn of the millennium.
FWIW, looking at vacancy statistics across the whole of the country can be misleading. They include houses that are vacant for any reason - including properties that are condemned, under renovation, or in the middle of nowhere where there are no jobs.
That latter point is key. As more and more economic activity has moved to white-collar coastal cities and away from rural or suburban blue-collar middle America, it's no surprise there are going to be vacancies in regions where the economy's been hollowed out. So we can conjecture that the record low vacancy rate is even more problematic, because those vacancies are likely less equally distributed to areas that need them.