Selecting cities, determining boundaries, mapping regions

What would you do if you wanted to understand urban regions? So many cities, so variable in size and geography – the task seems daunting. You might enjoy traveling to and studying a good batch of them, but these are large complex objects and the enterprise would take years. Or you might devour books and articles on the subject, also a protracted process, which would provide a skewed picture dominated by a limited number of much-studied cities. Or simply talk to the experts (who wrote those books and articles). Here is the story of how I learned.

Selecting cities worldwide

To get the big picture at the outset I pulled out maps, all sorts, and sketched the shapes and sizes of cities and especially how they are arranged relative to water bodies and mountains. Since I have lived in parts of North America, Europe, Latin America and Australia, initially the focus was on other areas, then gradually becoming worldwide. Quickly I was able to group the sketches into three big categories characterized by: (1) continent or geographic area; (2) location relative to rivers, bays, seacoasts, etc.; and (3) city size, as indicated by area. I decided that my mix of urban regions to be studied should include the typical range of variation within each of these groups, and that probably other useful categories or subcategories exist which should at least be represented.