New Westminster is a city in the Lower Mainland region of British Columbia, Canada, and a member municipality of the Metro Vancouver Regional District. It was founded by Major-General Richard Moody as the capital of the Colony of British Columbia in 1858 and continued in that role until the Mainland and Island colonies were merged in 1866. It was the British Columbia Mainland's largest city from that year until it was passed in population by Vancouver during the first decade of the 20th century.

The Lower Mainland is a geographic and cultural region of the mainland coast of British Columbia that generally comprises the regional districts of Metro Vancouver and the Fraser Valley. Home to approximately 3.05 million people as of the 2021 Canadian census, the Lower Mainland contains sixteen of the province's 30 most populous municipalities and approximately 60% of the province's total population.