Unless you’ve been living in a hole for the past five years, you’ll probably know that the world’s cities are getting bigger. Half the world’s population currently lives in them; by 2050, demographers predict it’ll be 70 per cent.

Some of those additional 20 per cent will live in new cities, created to meet the insatiable demand for an urban lifestyle. Sometimes, that’ll mean cities expanding; but sometimes, it’ll just mean cramming more people into existing ones.

To find out which cities will grow not just bigger, but more crowded, Bloomberg has put together a list predicting which will have the highest population density by 2025. Perhaps unsurprisingly, seven of the top 10 are in Latin America, a region whose cities are already teeming with informal slum settlements.

Here’s the top ten:

(You can view the full list here.)

Hong Kong doesn’t just take the top spot: it’s predicted to be nearly twice as crowded as second ranked Salvadar’s. It doesn’t take a genius to work out why: the city-state is an island, and an rich one at that, so there are many incentives to move there, but, short of expanding onto the water (something the city is actually considering) there’s no way for the city to expand outwards. It’s a similar situation in Singapore (also an island), and in Salvador (surrounded by water on three sides).

One thing that isn’t clear is the city definition used by Bloomberg to create the predictions. It’s possible they’ve used the same urban boundaries for the 1995 figure and the 2025 figure, despite the fact these boundaries will likely change. However, examining the same urban area’s population growth over 30 years is still useful – in cities with expanding suburbs, fewer people will need to live in the packed centre. In cities with nowhere to expand, like Hong Kong, the population of that urban centre will necessasrily just keep getting higher.

Another interesting metric the list explores is the cities’ percentage growth between 1995 and 2025, a period Bloomberg defines by that hazy metric, a “generation”. In Hong Kong, for example, its growth over that period is predicted to be 36 per cent. This may sound like a lot, but Brasilia, which is seventh on the list, is expected to grow by a whopping 119 per cent. Two cities in Saudi Arabia, Riyadh and Jiddah, are forecasted to grow by 167 per cent and 137 per cent apiece.

Another surprise is Atlanta, Georgia. In terms of density, it takes 40th place on the list, but its population is predicted to grow by 115 per cent. Here’s the top ten cities by growth:

A report in Arab News last year claimed that Saudi Arabia’s urban populations are increasing so rapidly largely because the central government is investing in urban areas far more than smaller settlements. These cities are also relatively new, with swathes still under construction: Jeddah is currently building an entirely new transport network to deal with its terrible traffic and swelling population.

The four US cities predicted to double or nearly double by 2025 have post-recession rebounding economies to thank. Houston’s oil industry is booming, while Phoenix is becoming a slightly improbably tourist destination (we hear the golf’s lovely).

The names on this list suggest that, as rising prices make bigger global cities more inaccessible, it might be less famous cities that’ll  take the brunt of the next wave of urban migration.