Celebrating his big accomplishment, McGowan said, "By being valedictorian, I think that I can change some people's perspective about my race specifically."
An all-boys Roman Catholic college preparatory school, St. Thomas was founded in 1900.
"The guys here are really competitive academically," said principal Aaron Dominguez. "They support each other. They hold each other up, but they're also vying to be the very, very best."
According to KHOU 11, valedictorians are nominated by their classmates and then the school's faculty makes their selection based on the students who received the most nominations.
McGowan plans to enroll at the University of Chicago to pursue political science. He hopes to attend law school and become an immigration attorney.