It is given a lot of importance and is a must for students who plan to do science related study in college. On the other hand, high school in America is so flexible that a lot of students who end up majoring in sciences in college do not take advanced maths and calculus in high school. In general, I found that at the end of their 1st year of university, math majors in the US are equivalent to high school graduates in India in terms of math study. The analytical thinking taught by mathematics is exactly what is required for software development. The flexibility of the American education system is its greatest strength and also its greatest weakness.
Students can choose among a host of classes and courses in high school and college.
This usually means that students in the US receive more exposure to a variety of subjects and hence, are more aware of their career options and opportunities. However, the downside is that they can avoid taking courses which are hard in their major. The computer science students in my department in the US are often criticized for avoiding a lot of important computer science courses by taking easier courses from other departments that fulfill their degree requirements. So, the system is designed in such a way that nearly everyone can pass the high-school level. This leads to lowering the standards at the high school, which in turn leads to lowering the standards for college entrance too and subsequent college programs.