How Important is the rank of a school in a certain specialty? I am interested in applying for PhD programs in discrete mathematics, but one of the schools I'm looking at isn't included in the top 10 rankings of discrete math programs (at least not according to US News: https://www.usnews.com/best-graduate-schools/top-science-schools/discrete-mathematics-rankings). The school I am looking at is an overall top 25 school in math, but just not in the top 10 for the specific area I am interested in. They do have several people (about 5) researching discrete math, so it is not a non-existent research area in this school.

The part that I am especially torn about is that if I were to go to this school, then I wouldn't have to move (and incidentally the city I currently live in is my favorite city), and I could likely keep my current job and just work at my job half-time. I figure that if I'd have to likely work 10-20 hours a week as a TA, it might be worth it just to do 20 hours a week at my current job with better pay. Also I should mention that so long as I do 20 hours a week at my current job, I will get tuition payed for, health insurance, 401k etc (all the benefits I currently have). My goal isn't to stay in industry, but to go into academia, and so I would need a really stellar dissertation since academia is so competitive. My question is therefore if you want to take the academia route, how important is (in shaping how good of a mathematician you will become) the ranking of a school in a certain specialty if its overall math ranking is good (top 25), and there are still several people doing research in that specialty?

EDIT:
I wouldn't be able to live in the same city as the school is located in. I'm in a city that is close by. How important is it to live near the campus when doing a PhD?
Don’t trust the US News grad school subfield rankings at all.  They’re based entirely on surveys and most people don’t actually know a lot about things outside their speciality and their university.  So you infamously end up with high ranking places that actually don’t have anyone in the subfield.

If you want to know how good a school is in a subfield you’ll have to look into it seriously yourself.  Ask people you know in that subfield, look up the research interests in the department, find out whether their have been grad students their recently, after you get accepted visit the dept and ask questions.

That said, I think in the US in math it’s a mistake to narrow down to a specialty before you go to grad school.  You have a year of grad school before you have to pick an advisor, and you’ll learn a lot in that year.  Plus you’re more likely to find a good advisor match if you are picking between 20 potential advisors and not 2.