 On early 20th century maps, Sallynoggin and Glenageary are indicated as being the same place, however, with the development of the local authority housing estate on the Townlands of Honeypark and Thomastown, Sallynoggin became a distinct area.Up to 1994 the boundary of Dún Laoghaire Borough Corporation left a section of the local authority housing outside the Dún Laoghaire area mainly Pearse Villas and a part of Pearse Street which were in the Dublin County Council area.With the formation of Dún Laoghaire, Rathdown County Council in 1994 the entire area of Sallynoggin, Rochestown, and surrounding areas were included in the new county.