While the Proud Boys’ membership is not public, Mr. Holt said the group appeared to be growing in small towns and counties.
Often, their presence has been enough to disrupt events. Last month, the school board in Beloit, Wis., said it canceled classes because some of the Proud Boys were at a local protest over mask requirements. In Orange County, Calif., the school board said in September that it would install metal detectors and hire extra security after several Proud Boys attended a meeting and threatened its members.
In New Hanover County, N.C., which has roughly 220,000 people and is two hours north of Charlotte, Stefanie Adams, the school board president, said she had read about the group’s increasing appearances and began tracking the reports closely.
Ms. Adams said she had an inkling that the Proud Boys might show up in her school district, which has 25,000 students. Because North Carolina law requires the county school board to vote on whether to continue a mask mandate for students each month, the district had handled many contentious meetings over the issue, she said.
“I figured we were on their radar, and that we might be next,” Ms. Adams said. “We knew we had to prepare for them coming to our town, too.”
Last month, Ms. Adams was notified by the board’s head of security, which she had hired for the monthly meetings, that some Proud Boys were outside the building for the mask mandate vote.
Five Proud Boys eventually entered the room and stood in the back, Ms. Adams said. They folded their arms across their tactical vests and wore matching T-shirts with images of a rooster, the group’s insignia. While they did not speak publicly, video footage from the two-hour meeting showed them clapping and cheering as anti-mask speakers made their case.