In this video, we are going to use the ArcGIS geography visualizer to visualise the major cities of the world. Now, to do this, the first thing I'm going to do is change the base map. So we've currently got an imagery hybrid map on the screen and that combined satellite imagery with the borders of the countries. We call that hybrid map. I'm going to change that. So I'm gonna come to the bottom toolbar. I'm going to click on the base map, and I'm going to click on the chartered territory map. And that just makes it a little bit easier to see where the different countries are, and also gives us lots of reference points by having these lines of latitude running around the world. I'm then going to add a layer of data onto the map. So if I come to the bottom toolbar again, I'm going to click on this Add Layer button. Now, this layer of data I can actually get to in two ways. I can actually get to it if I click on the open map or if I add a layer. But I'm going to add a layer and I'm going to go to where it says Cities of the World. And we can see what it is, explore how the population of urban areas changes, and we can see where it's come from, the United Nations Departments of Economic and Social Affairs. We can see it's published in 2018. So that gives a little bit of information about it. I'm going to click on the Add button. And when I do that, you will see that there is a little 1 popped up where it says map players. I can now close this popup and you can see that there's lots of circles that have now come onto this map. Now, to know what these circles mean, I can come to the bottom toolbar and click Legend and it shows you what they mean. So we can see that the size of the circle shows us how big the population is. So, you know, this size is below 37 million, this size is 28 million, this size 20 million, and so on and so forth. We can see at the bottom there that the smallest circle is cities over 300,000 people. So we're not gonna have cities which are below 300,000 people. So this isn't all the cities of the world, it's what they term as as major cities. Now, first, a few warnings about this map. I'm going to zoom in on the United Kingdom here. I've clicked on the United Kingdom and I've dragged it to the centre of the screen and I'm now using the scroll wheel of the mouse to zoom in. So we can see here, for example, that there's Plymouth and there's no red dot there. And that's because Plymouth, it's a pretty big city, but it's under 300,000 people. So it is important to remember that that's where this starts. It's really important on these maps as well that we actually make sure that the data is valid. So there's often slight issues with data that we need to be aware of. And I'll show you an example here. If I zoom in, and I'm going to zoom into this area around Leeds and Bradford, and you'll notice that there's a red dot around Bradford here, but not Leeds. Now I know that Leeds is a pretty major city, over 800,000 people, there's estimates for the population of Leeds and yet it's not on. Bradford is also a big city, maybe around 550,000 people. And there is a circle there, and if I click on this, you can see that it's actually given me a population, but it's actually said West Yorkshire. Now West Yorkshire's a county. So what they've done here is they've basically added the population of multiple cities and, you know, wider area to come up with one city. Now that's unusual, it doesn't normally do that, but it's just important to see some limitations of the data so that when we draw conclusions, we know that we have to understand the limitations of our conclusions and some of the problems that we might have to think about when evaluating our data. The other issue when we're looking at population is thinking about this figure as actually being, you know, try and decide how accurate the figure is. So if I take this example here, if I click on Manchester, we can see that there's a population here of over 2. 7 million people. So that's a really big area. But the question is, is where does Manchester start and where does it stop? Now that figure for 2. 7 million people is the greater Manchester area includes places like Stockport. If I was to move that boundary in, I could actually say that Manchester's only got around half a million people. It just depends about where I decide the outskirts of Manchester are. Often this becomes a problem where, like Manchester, we've had a place which has expanded over time and has actually merged with other towns. So again, when we look at these populations, we have to understand there are problems or decisions that have had to be made to decide about where the boundaries of the cities are, and that is going to affect our population figures. And that often means we often get different population figures for the same place. However, having said all that, this is a really useful map to show us lots of information about major cities around the world. And what we can do is we can describe where cities are, and that's maybe cities over 300,000, but also maybe the mega cities over 10 million, by looking at the map and examining patterns. We can look at maybe the city the furthest south in the world to see, you know, how far south or north cities stretch. So for example, this city down here is Christchurch and we can see, you know, population around 400,000 now it's just north of 45 degrees south. And we can see that we don't have major cities south of that line. That's largely because of the lack of landmass there, but it gives us a point that we can then describe. Now, if we look carefully, there is no city further north than this city. So if I click on this, this is Arkhangelsk in Russia. And if I zoom in, it gives us the lines of latitude, which help us describe where it is. And we can see it's just south of 65 degrees north. So we can say that we don't really get major cities north of 65 degrees north. We can also look for these really big circles to see where the mega cities are, and if we click on them, we can see just how big they are. So this is Tokyo and Japan, and we can see population of over 37 million. Mega cities are defined as populations with over 10 million. So this is definitely a mega city. And we can see from the map, for example, that we have a concentration now of mega cities in China and India. So what I can do is I could zoom into these countries and I could maybe count the number of cities, I can count the number of mega cities, I could find out what they are. And this allows us to visualise the cities of the world and describe the geographical patterns of where cities can be found and where mega cities can be found.