Elgin County ( ) is a county composed of seven municipalities in Ontario, Canada with a 2021 population of 51,912. Its population centres are Aylmer, Port Stanley, Belmont, Dutton and West Lorne. The county seat is St. Thomas, which is separated from the county but within its geographic boundary.
Elgin County is composed of seven incorporated municipalities (in order of population):
The City of St. Thomas is geographically within the boundaries of Elgin County and part of the Elgin census division, but is separated from county administration.
Originally Elgin County was once part of Middlesex County, which was reorganized as the United Counties of Middlesex and Elgin in 1851. Elgin was named after Lord Elgin, who was Governor General of Canada at the time.
The County was separated from Middlesex in September 1853.
As a census division in the 2021 Census of Population conducted by Statistics Canada, Elgin County had a population of living in of its total private dwellings, a change of from its 2016 population of . With a land area of , it had a population density of in 2021.