To determine the best private high school in every state, 24/7 Wall St. reviewed rankings for all private schools from the 2021 Best Private High Schools in America list produced by school and neighborhood data clearinghouse Niche. Niche ranks private schools based on average SAT and ACT scores, the rank of the colleges that students are most interested in or go on to attend, college enrollment, culture and diversity, student-teacher ratio, and parent and student surveys. Data on the number of students, average SAT score, and annual tuition also came from Niche. When tuition data was not available from Niche, outside sources were used. Unless otherwise noted, all school-specific figures came directly from Niche profiles. All references to school rankings within states are based on Niche data and are out of private schools in the state only.