Duncan (City) confirmed 12 December 1939 on 92B.

Source: BC place name cards, or correspondence to/from BC's Chief Geographer or BC Geographical Names Office

Duncan's Station Post Office opened 1 October 1899. City of Duncan incorporated 4 March 1912. Post office name changed to Duncan Post Office 1 July 1926. See also the Municipality's own website.

Source: BC place name cards, or correspondence to/from BC's Chief Geographer or BC Geographical Names Office

Named after William Chalmers Duncan, whose farm, Alderlea, was located here in the 1860's. Duncan was born 1836 in Sarnia, Ontario, arrived in Victoria in May 1862 and was one of a party of one hundred settlers that Governor Douglas took to Cowichan Bay in August that year. When the Esquimalt and Nanaimo Railway was opened August 1886, the level crossing near the late William Duncan's farm was named Duncan's Crossing. The following year E&NR opened Duncan's Station at the crossing. Mr. Duncan's original holding forms a large part of what is now the city area. William Duncan's son, Kenneth, became the first mayor of Duncan. See also obituary of Mrs. Sarah Annie Duncan in Victoria Times 29 January 1937.

Source: BC place name cards, or correspondence to/from BC's Chief Geographer or BC Geographical Names Office

After William Chalmers Duncan, pioneer of 1862. So-named in 1887, when E&NR opened a station here. Previous name Alderlea.

Source: Provincial Archives' Place Names File (the "Harvey File") compiled 1945-1950 by A.G. Harvey from various sources, with subsequent additions