Where you went to HS is a common question in my upper middle class neighborhood.
The only reason anyone has asked me about HS since i graduated from it…was if they knew my home town area. They were just curious where I went to HS.
I will say, I had to complete an online job application a couple of years ago, and one of the questions was where i graduated from high school…and when. I thought it odd. It’s very old news in my case, and the only point served was to perhaps figure out my age!
Sounds like it matters in Baltimore.
Around Pittsburgh, it’s a trigger for high school football talk, high school band talk, high school social activity talk, “did you know xxxx - s/he went to school there”, etc. Completely a social thing, nothing to do with jobs, careers, etc.
Folks have pretty fierce loyalties to high school sports teams, even decades after they’ve graduated. Given the very tight-knit nature of the town, it’s just a very common conversation starter.
As the area is mostly an exporter of population, I get often get confused looks when I answer “where did you go to high school” with “New Jersey”.
In our son’s case, his high school friends and network are just as important to him as his college friends and network. His high school network is tight and active and has been a valuable resource for him. For example, he recently received an invitation to attend a webinar with graduates who are now venture capitalists to learn how VCs evaluate opportunities and how to go about securing investment. He found the webinar very informative and made contacts that could be valuable in the future to the company he co-owns with another officer. Also, his high school network was instrumental in job opportunities for several of his classmates as they were graduating from college. Because high school was a boarding experience for him, he has a deep and enduring bond with his classmates and feels the same level of commitment to them as he does to his band of brothers in the Army. I know this is not the typical high school experience, but where he went to high school does matter to him.
My kids went to a pretty well known private school in NJ. D1 said some people at work would tease her or give her a second look.
I was having a personal dispute with a company. Their lawyer, all the way on the other side coast, tried to chat me up with where I lived and where my kids went to high school because he was also from NJ. It turned out he graduated from my kids’ school. I got everything I wanted. 
I also had few CC’ers from my kids’ school who PM’ed me to offer some assistance a few times.
I have family members who received interview offers from very prestigious employers during slow economic times. Although all positions required advanced degrees, the interviews were offered in large part due to the prep school attended. None of these were for first time jobs.
I went to one of the specialized high schools in NYC. While I lived there as an adult, it definitely mattered. People always ask where did you go to high school and are impressed when you name one of the specialized high schools or one of the top private schools. Alums are fiercely loyal so there’s a great network on the NE. I’m now in a different part of the country so it doesn’t matter as much, but I can still call on one of my classmates or alumni to make an introduction to someone in my part of the country.
Re: Baltimore. As stated above there are a few great public schools in the city that are “prestigious”. There are also great private schools available. Anyone with any means would not send their child to any of the other public schools as they are abysmal in comparison. It certainly matters if you attend high school in Baltimore City where you go. As stated there are also network and alumni considerations that can lead to benefits later in life.
Suppose two people from Baltimore are both graduates from the same college in the same major with the same GPA. One attended one of the “prestigious” high schools, while the other attended an ordinary public high school.
How much does the high school matter between them for getting jobs or other situations in the Baltimore area?
^^^It’s definitely a thumb on the scale. If everything else is exactly the same, I think the job would go to the fellow alum.
I definitely agree about NYC.