In Australia, and a number of European countries, Calculus takes up the last two years of high school in the advanced stream (for anybody intending to go to university and take Law, Engineering, Medicine, Physics, Chem, etc).

Interestingly in serious university mathematics when looking at the foundations of mathematics, Linear Algebra is a functional prerequisite of multivariate calculus and anything higher dimensional as LA provides a literal basis for abstract spaces and local approximations to continuous functions, etc.

(Often the two are formally taught in parallel)

It’s the same in the US. My son is in 10th grade doing Pre-Calculus now and should be in AP Calculus next year.

If you don’t take the AP class to test out of it, you’d have to take it first in college though.

I imagine many people strong enough in math to pursue sciences will go the AP route and test out of it, but not everybody takes the same path.

At the place I went, they designed the curriculum around students that came in without it. But I guess testing out gives room for a gen-ed.

I dunno. The vibe in high school’s hardest math class and college’s easiest math class is kinda different. Might be worth doing both, haha. Easy A, too.

I generally think it should be taught along calc 3 (advanced integration and differential equations), as there's decent conceptual overlap and basic calculus helps weed out those who might not be ready for a more rigorous course.

Also to clarify wrt calculus, it is very common for university-track students to take AP calculus in high school, which allows them to take an examination that most universities accept to prove mastery of the equivalent to calc 1 or calc 1+2 depending on the examination.