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Boulogne-Billancourt, a bustling city located in the Hauts-de-Seine department of France, had a population of 121,334 as of 2018. This figure showcases the steady growth the city has experienced over the years, becoming one of the most populous cities in the Île-de-France region. With a diverse population and a thriving economy, Boulogne-Billancourt continues to attract both residents and businesses, contributing to its growing significance within the region.