Completion of the highest level of math offered at your high school (often calculus, may be precalculus at high schools that do not offer calculus) is usually fine in terms of “four years of college prep math”. Note that this requirement or recommendation is often given further explanation about what math courses are expected to be completed.
University of Washington is an exception, since it wants to see students take a math or math-using science course as a high school senior (may be a problem for a student who completes all such offerings available in his/her high school in junior year, and there is no convenient nearby college to take such a course at). https://admit.washington.edu/Admission/Freshmen/CADR#math-based-quantitative