Public transit provides connections from Duncan to the surrounding communities including Lake Cowichan, Crofton, Chemainus, and Ladysmith as well as communities to the south including Cobble Hill, Shawnigan Lake and Mill Bay.

Duncan is serviced by the neighbouring Maple Bay Airport (YAQ) in North Cowichan, which offers services to Vancouver Downtown, Vancouver Airport, Ganges on Salt Spring Island and Bedwell Harbour on Pender Island.

He arrived in Victoria in May 1862, then in August of that year he was one of the party of a 78 settlers which Governor Douglas took to Cowichan Bay.

No stop had been scheduled at Alderlea for the inaugural train bearing Sir John A. Macdonald and Robert Dunsmuir.

[7] After a particularly wet winter in 1911–1912, a vote was held to make Duncan a distinct city, and it was incorporated on 4 March 1912.

[8] With the enlargement of North Cowichan in the ensuing decades, there was an effort to re-unite the two municipalities, though a referndum on the matter in June 1978 was soundly defeated.

At its largest point, Duncan's Chinatown included six Chinese families and 30 merchants who supplied goods and services to the loggers, millworkers, cannery and mine workers in the area.

[11] In the 1980s, the city was noted in coverage related to the 1985 bombings at Narita Airport in Japan and aboard Air India Flight 182, Canada's largest murder case.

Less than two weeks prior to the bombings, Reyat and suspected Air India mastermind Talwinder Singh Parmar were observed testing explosives in the woods outside of Duncan by the Canadian Security Intelligence Service (CSIS).

The City had 44 totem poles in the collection, however one was destroyed in an auto accident, one was gifted to Kaikohe, New Zealand and one returned to earth.

[25] The Cowichan Historical Society (Museum) provides free totem tours in the summer months.

Duncan has a large Indigenous community and is the traditional home of the Cowichan Tribes, who are the largest band among the Coast Salish people.

Vancouver Island University (formerly Malaspina University-College) has a regional campus in the Municipality of North Cowichan, bordering Duncan, that offers a Bachelor of Education degree as well as programs and courses in university transfer, access, trades and applied technology, health and human services, and career and academic preparation.