In the United States, a high school diploma is normally conferred based on taking a certain number of courses, not on reaching a particular standard of achievement. There are no exams that all students nationwide must pass in order to be eligible for university study. Admission standards vary from institution to institution to the extent that some open-enrollment colleges and universities permit almost any student to attend. Unless students are among the few who plan on applying to highly selective institutions, there are no external incentives encouraging them to work hard and do well in difficult courses. Good grades were once the required currency for college admission, and a high school diploma was once a pretty good ticket to a decent job. But today good grades aren't necessary to enter most colleges.
The two exams that most commonly serve as a gateway to college in the United States, the SAT and ACT, are not based on the curriculum students study in school. College-bound students in the United States are not required to take any advanced subject-specific exams. The most common requirement of college-bound students is that they have obtained a minimal number of course credits, though this is not necessarily a reliable indicator of their academic performance. Very high grades and test scores, correlate strongly with success. Very low grades and scores usually mean failure. Those who take AP exams may do so in any subject in which the exams are offered, but there are no government or university requirements in terms of subject areas or numbers of exams to be taken. Current college/university standards require that institutions monitor and assess the progress of candidates, establish and publish criteria or outcomes for exit, and provide candidates appropriate academic and professional advisement from admission through completion of their education programs.
In New York State, all students have the option of taking "Regents" (college preparatory-level) courses during their secondary years and then taking Regents exams before they graduate. Students who do pass the exams will have this noted on their diplomas for all to see, and New York's state university system gives preference to students who score well on Regents exams. New York is the only state in which a large number of high school graduates participate in a curriculum-based examination system. The system works; notably, when you control for family income, parental education, race and gender, New York has the highest average SAT scores of any state.
Colleges and Universities enacting higher admission standards would need to notify applicants that to be accepted at this particular college/university, students will have to complete a college-preparatory curriculum and attain a minimum GPA, SAT/ACT score, or class rank. This may cause a decrease in enrollment due to lack of qualified applicants. However, the initial loss in enrollment can be made up over time if potential applicants realized that the quality of the institution had improved with increased standards.
