According to NBISD officials, Clark, a 1999 graduate of NBHS, was elected to the board in 2013 and has served as vice president for the past year. He had 1,473 votes.
Heefner, a resident of New Braunfels for the past 33 years and a former teacher in the district, finished second with 1,252 votes.
Trevino had 839 votes. Keith D. Smith, who was first elected to the board in 2010, was also re-elected to another three-year term on the board for single member District 1. He was unopposed and will served his fourth term as a board member.
The candidates will be sworn in on May 20.