Is international Ph.D. student's stipend enough to support a partner in the U.S.? Something that is not clear by any kind of research is this: 


  Is associateship (which waives tuition and fees) stipend enough (annually 20k) for a student and his wife to take care of all their necessities and carry on during the whole Ph.D. period, without any other financial support?


I'm just asking in general and I know costs may vary a lot between different places. But since being a bit more specific is better, let's talk about the cities with medium cost of living according to Cost of Living Index 2018. For example, Columbus or Minneapolis is around 60 vs. New York that is 100.
I am hoping to start a grad program in one of those medium cost-of-living cities, and have been doing lots of research. Since it sounds like I'm more familiar with the US than you, I'll give you what I've learned.

This will of course depend on your standard of living. I assume because you are married, you would like to live in your own apartment/house and not live in one bedroom in a four-bedroom house. This answer is based on that.

As another caveat, I would say I'm moving from a very expensive area, so it's possible I'm overestimating other expenses based on my experience here. 

At more than $30k (the value of some awards), I feel like I could minimally support myself and my wife (who is also going back to school). We also have a nice chunk of savings that we've been accruing for two years that helps me feel better about living on the stipend.

At less than that, around $25k, we would plan on my wife working 8-12 hours a week to supplement my income. 

Those numbers are totally unlivable in high cost-of-living areas, like where I live now. I couldn't imagine trying to live here on less than $50k combined; and that's a totally unachievable PhD stipend.

Tl;dr:


&lt; $20k - Not a chance, would expect my partner to work at least part
time
$20-25k - Doable, with decent savings and a few hours of work on your partner's side.
$25-32k - Much more doable, but still tight living
>$35k - As comfortable as you can be on a PhD stipend.