Most of it is part of Metro Vancouver Electoral Area A; the remainder is Barnston Island Indian Reserve No.

3, which is outside Electoral Area A limits and under the governance of the Katzie First Nation, headquartered across the river at their main reserve in Pitt Meadows.

Statistics Canada defines the island as Vancouver CMA Census Tract 0251.00 of British Columbia.

The island was named for George Barnston, a Hudson's Bay Company clerk, who travelled with Chief Factor James McMillan to found Fort Langley in 1827.

[5] Statistics Canada subsequently amended the 2011 census results to a population of 47 living in 18 of its 18 total dwellings, a -4.3% change from 2006.