My observations concur that it's driven by the interest the school places on math achievement, and math competitions specifically.

My DD15 participates on a math team at a local university, and has students from a school just a few miles down the road. Their school has had an AMC12 Club for several years, and has regularly placed students at the top performance levels of Mathcounts, AMC8, AMC10, etc. over the last 3-4 years that I've been involved.

My duaghter's school seems to have no interest in the subject. There is one other student from her school in the university math program, and he tried to start a math club at school. I even went in and met with the head of the HS math department to volunteer and help out however I could. He said there were challenges finding a teacher to sponsor the club. That would pretty much consist of signing a sponsorship form and staying with the club for a 2 hour meeting once a week.

My daughter and the other student said they would create and teach the material, and I would help them.

It went nowhere. Not a single math teacher among 15+ in IHS/SHS would spare 2 hours a week to support students who wanted to run a math club. After all the of the "STEM is so important" hype, this was quite disappointing.

My pestering at least got them to sponsor the AMC tests for the first time. 70+ kids took the test and, not surprisingly based on the lack of supplemental work, scored mostly around average. My daughter qualified for AIME, her classmate came just short, and they were way ahead of everyone else.

I exchanged messages with the head of the HS gifted program to schedule the AIME, and thanked him for offering it. He said he sponsored it for this year as a trial, but wasn't convinced of the value of it.

So our school seems to have math teachers with no interest in supporting a math club, and a gifted teacher who doesn't value advanced math competition.

The school down the road has at least 6-8 AIME qualifiers. Their team of 4 at Mathcounts state finals finished 1,2,10, and 18. My daughter at 15 was the only one from our team to place in the top 30 (they only publish the top 1/3). Our team "coach" didn't even make the trip - she left if up to parents to get the kids there to compete.

On an SAT and other measures, the schools are quite comparable. But achievement is different than talent. I don't doubt many in our school could advance quickly given the opportunity. But when math teachers don't support advanced math achievement, it's hard for parents to do it on their own.

I'm fortunate to have been an AHSME award winner and have some background and passion in the area, so we've lived on AoPS for the last couple of years. But it's hard to do without school support for most kids.