Teachers and staff from two Boston charter schools voted Wednesday to unionize. More than 60 employees at City on a Hill’s Circuit Street and Dudley Square schools submitted cards to join the Boston Teachers’ Union, making it the first commonwealth charter school in the city to do so, according to union officials.

A teacher organizing the vote said he wanted to stem high turnover at the schools.

“Turnover is especially high in the charter schools, and in our charter school in particular, because we're not paid equitably,” said Max McCullough, a history teacher at Circuit Street. “People can't raise a family. A lot of times people can't afford to live in the city on the salaries we're being paid.”

Boston Teachers Union president Jessica Tang called the move “courageous.”

City on a Hill officials did not return calls for comment. In addition to two high schools in Boston, the City on a Hill network runs a charter high school in New Bedford.

Our coverage of K-12 education is made possible with support from the Nellie Mae Education Foundation.