Sanmenxia's 2021 population is now estimated at 579,273. In 1950, the population of Sanmenxia was 10,448. Sanmenxia has grown by 17,904 since 2015, which represents a 3.19% annual change. These population estimates and projections come from the latest revision of the UN World Urbanization Prospects. These estimates represent the Urban agglomeration of Sanmenxia, which typically includes Sanmenxia's population in addition to adjacent suburban areas.