Laos' population was estimated at about 6,48 million in July 2011, dispersed unevenly across the country. Most people live in valleys of the Mekong River and its tributaries. Vientiane Prefecture, which includes Vientiane, the capital and largest city of the country, had about 569,000 residents in 1999. The country's population density is 23.4/km².
In March 2005, the total population was 5.62 million (2.82 million females, 2.80 million males) in the 2005 census, an increase of 1 047 000 since the previous 1995 census.