In 1954, Hanoi had 53,000 people and covered 152km2. In 1961, the city was expanded to 584km2 and had 91,000 people. In 1978, the National Assembly decided to expand Hanoi for the second time to 2,136km2 and with the population of 2.5 million. In 1991, the city area was reduced to 924km2, but its population still reached more than 2 million. During the 1990s, along with urbanization of suburban areas, Hanoi’s population stably increased and climbed to 2.672 million in 1999.

Hanoi’s current population density was different between inner and suburban districts. In the city, the average density is 1.979 people/km2, but in Dong Da district (formerly called as Hoan Kiem district), the figure reaches up to 35,341 people /km2. Meanwhile, in outskirts district like Soc Son, Ba Vi and My Duc, the density is only less than 1,000 people /km2.
Regarding population structure, according to statistics of 1999, residents in Hanoi and ha Tay are mainly King people, accounting for 99.1% of their total population. Other people such as Dao, Muong and Tay make up just 0.9%. The census showed that the whole city had 2.632 urban residents, equal to 41.2% of its total population and 3.816 rural people, making up 58.1%.