Private High Schools in New Jersey

Pingry had 12 National Merit Semifinalists, Newark Academy had 7 (see the 2nd link), and Delbarton had 1 for Class of 2018.

Interestingly, Oratory Prep had 3 and is a smaller school. Seton Hall Prep had 2 and Christian Brothers Academy had 3.

It is much harder to make National Merit Semifinalist (223 index score) than National Merit Commended (213 index score).

https://www.mycentraljersey.com/story/news/education/2017/09/13/national-merit-scholarship-2018-semifinalists-central-jersey/659956001/

https://www.scribd.com/document/358901119/Semifinalists-in-the-2018-National-Merit-Scholarship-Program#from_embed