What is this a map of?

[hbelkins]

So, what is the map, anyway? No one ever really said...

Its purpose is to show all towns and cities of a certain size (>5000, for example). So, the insets are only for those areas where it's necessary to zoom in on a closely-packed bunch of municipalities.

Then why this?

"Old" is what I've been told- probably 50s to 70s

The insets are for Chicago, Cleveland, Cincinnati, Pittsburgh, Scranton, and Los Angeles

There are a lot of cities bigger than Cleveland, Cincy, Pgh and Scranton.

The insets are oddly chosen.

[NE2]

They're chosen because they have a number of separately-incorporated suburbs with that population. Whether that actually matters in the real world is doubtful.

[empirestate]

So, what is the map, anyway? No one ever really said...

Its purpose is to show all towns and cities of a certain size (>5000, for example). So, the insets are only for those areas where it's necessary to zoom in on a closely-packed bunch of municipalities.

Then why this?

The insets are for Chicago, Cleveland, Cincinnati, Pittsburgh, Scranton, and Los Angeles

There are a lot of cities bigger than Cleveland, Cincy, Pgh and Scranton.

The insets are oddly chosen.

You actually quoted the explanation above..."the insets are only for those areas where it's necessary to zoom in on a closely-packed bunch of municipalities." That is, Cleveland is surrounded by a lot of other cities having a population of 5000 or more (or whatever the threshold is). So, they made an inset to display them at a larger scale. The population of the principal city is irrelevant; only the number of other qualifying cities surrounding it. A city of 50 million people with no other incorporated places near it wouldn't need an inset.

They're chosen because they have a number of separately-incorporated suburbs with that population. Whether that actually matters in the real world is doubtful.

Well, it's sold at least two maps that we can account for so far. 

(And sorry I couldn't remove more of that doubt in your mind, but I don't think I can explain any more thoroughly how the information might be useful...but no worry, as we can see this map is a confusing artifact!

[NE2]

My problem is that it's arbitrarily useful. Showing a separately-incorporated suburb of 5000 people is no more useful than showing a suburb of 5000 that has been annexed into the main city or showing two adjacent suburbs of 2500 each.

[empirestate]

The map is a tool to gain information, and the parameters within which it displays that information will have to be arbitrary to some extent. If you're looking for overall demographic patterns and population distribution around urban centers, then yes, a map that imposes municipal borders on that information might obscure what you're looking for. Therefore, you probably wouldn't have bought the map we're talking about.

But I've described a different use, where a number of cities are disseminated by their municipal names (well, more often by their postal city names, but that's a different kettle of fish). If I want to mark them all on a map, I'll have better luck if the map shows place names that might correspond to the list I've been given. I don't care about their population per se, but the mapmaker has chosen that parameter to determine what information to include, and that choice will tend to line up pretty well (though not exactly) with the list in my hand. Obviously it would line up even better if the mapmaker published a map of all of the venues in the country that I might end up in, but that's a pretty narrow niche of interest. (A ZIP code map would also be useful, but I'd have to take the extra step of translating ZIP codes into city names.)

And of course, there are plenty of other applications for a map based on municipalities. I can see it hanging handsomely on a wall at the U. S. Conference of Mayors' office.

So, in short, don't make too much of the population threshold...that decides what goes onto the map, because something has to decide, but how you use the information may have nothing to do with population.

Hope that clears it up a little more!

[PAHighways]

"Old" is what I've been told- probably 50s to 70s

The insets are for Chicago, Cleveland, Cincinnati, Pittsburgh, Scranton, and Los Angeles

There are a lot of cities bigger than Cleveland, Cincy, Pgh and Scranton.

The insets are oddly chosen.

The City of Pittsburgh's population was in the 500,000-600,000 range depending on when this map was printed.