The number of cities in the world more than doubled from 5,851 in 1975 to .. ......... by 2025. Their share of the global population grew from 31 to 45 per cent over the same period. Projections indicate that by 2050, there could be more than 15,000 cities worldwide, most of which (over 12,000) will still be relatively small with fewer than 250,000 inhabitants. nities worldwide, most of which (over 12,000) will still be