We're talking metro area, not city. If the city is 1M, it's metro area is likely 1.5 to 3 million. If the metro area is 1m then the city is probably 750k to 350k people.
The post above said "The Concepción metro area is 1 million people" which means the city itself is much smaller. In fact, Wikipedia says it's 200k people, 1m metro area
Just a quibble about the metro to city population ratio... I think it's usually a lot higher than 1.5 or 3 to 1. Portland where I live has a population of around 650k (city) and 2.6M (metro). So about 4:1. And it's one of the less spread out metro areas in the US. The LA metro has about 18.5M and the city itself about 4M. Chicago is also about 4:1. NYC is the exception at closer to 2.5:1.
Just having grown up in LA (the city), I think there's a cognitive bias in these places against recognizing just how freakin large they are when you live there. There are large corners of my home metro area I've never been to at all, whose people I would almost never interact with... and I say that as a former taxi driver! Of course, taxi driving in LA was always balkanized so you'd need separate licenses to pick up in this or that suburb... very Snow Crash-like even in the 90s.
The post above said "The Concepción metro area is 1 million people" which means the city itself is much smaller. In fact, Wikipedia says it's 200k people, 1m metro area