In 1894, he was elected to the New York State Assembly as a Democrat, representing the Kings County 1st District.
[11] In his last year in the Assembly, he was appointed a member of the Hughes-Armstrong Insurance Investigating Committee.
[12] In 1906, Mayor George B. McClellan Jr. appointed McKeown Deputy Tenement House Commissioner, in charge of Brooklyn, Queens, and Richmond.
In 1911, Comptroller Somers appointed him Supervisor of Private Bank Examiners.
Their children were Marie, Esther, Majorie, Virginia, Helen, John A., James Mitchell, and Frank E. He was a member of the Roman Catholic Orphan Asylum Society, the Knights of Columbus, St. Patrick's Society, the St. James Holy Name Society, and the Kings County Democratic Committee.