I have a new not-so-serious goal. I say not-so-serious because I'm busy with lots of other things and who knows if/when I'll actually get around to this. So let's just say that this goal is based on a strong interest. I would like to visit the 10 largest urban areas in the world.

I was careful to say urban areas, because largest cities can be misleading. City proper boundaries are an arbitrary measure. What matters more are the built up areas.

I have already been to a handful of them, namely the ones centered around Tokyo, Dhaka, and Mexico City. But there are more on the list that I haven't been to.

There are, however, two immediate challenges with setting a not-so-serious goal like this one. The first is that it's not easy to come up with a definitive list of the largest urban areas. It's nuanced and, for some cities, population estimates are very much rough estimates.

The second is that population figures are constantly changing. So by the time I get around to this, many of the largest cities might be in Africa (current forecast for this century) and I may be checking off the wrong list.

But let's not let perfect be the enemy of good. Here's what I came up with. And by "what I came up with," I mean that I asked ChatGPT its opinion. This is the list I got:

Then I asked the question in a slightly different way and got this list:

Then I asked it to tell me its definition of metropolitan area vs. urban agglomeration:

Finally, I asked it why Lagos, Nigeria was not on the list. Current estimates place this urban region at more than 20 million people (which would place it ahead of New York in the first list), but I don't think anyone really knows for sure. Whatever the current number, it is widely understood to be one of the fastest growing city regions in the world. This is how ChatGPT responded:

I'm a little torn because high on my list of cities to visit are São Paulo and Seoul. And they don't seem to be finding themselves on the same list. I'm also very curious to see Lagos, and I have a suspicion that it's much larger than official estimates. Regardless, there are some clearly big cities to check off. India and China would be good places to start. So I better get to work. Or not. Since this is a not-so-serious goal.

PLOS One recently published a paper and a set of maps that looks at commuter flows across the United States (over 4 million data points). The objective was to identify all of the country’s “megaregions.”

Here is one of those maps. I think it says a lot.

We often think of cities as having discrete boundaries and population counts, but the reality is that studies and maps such as these provide a much better sense of the overall economic geography of a place.

I have a new not-so-serious goal. I say not-so-serious because I'm busy with lots of other things and who knows if/when I'll actually get around to this. So let's just say that this goal is based on a strong interest. I would like to visit the 10 largest urban areas in the world.

I was careful to say urban areas, because largest cities can be misleading. City proper boundaries are an arbitrary measure. What matters more are the built up areas.

I have already been to a handful of them, namely the ones centered around Tokyo, Dhaka, and Mexico City. But there are more on the list that I haven't been to.

There are, however, two immediate challenges with setting a not-so-serious goal like this one. The first is that it's not easy to come up with a definitive list of the largest urban areas. It's nuanced and, for some cities, population estimates are very much rough estimates.

The second is that population figures are constantly changing. So by the time I get around to this, many of the largest cities might be in Africa (current forecast for this century) and I may be checking off the wrong list.

But let's not let perfect be the enemy of good. Here's what I came up with. And by "what I came up with," I mean that I asked ChatGPT its opinion. This is the list I got:

Then I asked the question in a slightly different way and got this list:

Then I asked it to tell me its definition of metropolitan area vs. urban agglomeration:

Finally, I asked it why Lagos, Nigeria was not on the list. Current estimates place this urban region at more than 20 million people (which would place it ahead of New York in the first list), but I don't think anyone really knows for sure. Whatever the current number, it is widely understood to be one of the fastest growing city regions in the world. This is how ChatGPT responded:

I'm a little torn because high on my list of cities to visit are São Paulo and Seoul. And they don't seem to be finding themselves on the same list. I'm also very curious to see Lagos, and I have a suspicion that it's much larger than official estimates. Regardless, there are some clearly big cities to check off. India and China would be good places to start. So I better get to work. Or not. Since this is a not-so-serious goal.

PLOS One recently published a paper and a set of maps that looks at commuter flows across the United States (over 4 million data points). The objective was to identify all of the country’s “megaregions.”

Here is one of those maps. I think it says a lot.

We often think of cities as having discrete boundaries and population counts, but the reality is that studies and maps such as these provide a much better sense of the overall economic geography of a place.