Urban Population to Overtake Country Dwellers for First Time: Next Year to See Landmark in Urban Migration UN Says More Than 1 Billion Will Live in Slums in 2007. More people will live in cities than in the countryside next year, and a growing number will be living in slums. The UN report says the number of slum dwellers will pass the 1bn mark in 2007. Urban growth and slum expansion rates are nearly identical in some regions. For a long time we suspected that the optimistic picture of cities did not reflect reality.