McKinney Mayor George Fuller said the situation was a result of a legal requirement in the city charter that says councilmembers must live inside the district they serve.
At the meeting, Fuller told Thornton that he knew he believed he was a District 1 resident and had been before redistricting.
City Secretary Empress Drane addressed council members Tuesday night, saying it was her responsibility to confirm the residency of an appointed or elected city council member and that she had made a regrettable mistake. This was not a mistake or error with any harmful intent or any misleading intent. But it was really an honest mistake or oversight, she said.