02 March 2009

The Perlis Of News Map Design: Double-Check That Graphic Scale

1960.Map design, of course, is one of the monkeys on my back, and my interest in urban growth caused me to stumble on a little gem.

Spokane, Washington, is on the verge of an historic annexation. Between it and a little suburban community about three or four miles west of the city limits–a place called Airway Heights–is an area called the West Plains. It's been served by Spokane city services for a while and encompasses Spokane International Airport; a small area on the east side of Airway Heights is attractive to that town because, due to urban growth, it represents an opportunity for an increase in the municipal tax base.

When I first heard about the possibility of annexation (strangely enough, on KPOJ) well, you know me, the first thing I tried to do was find a map of the area concerned. I'm incredibly addicted to seeing the footprint of a city's incorporated area.

None was forthcoming. Until I checked now: this map now adorns the article in the Spokesman-Review:

That does seem historically large, especially compared to the graphic scale on the right side of the map there.

But, hang on a moment ... that scale says 5 miles. The news story says that Airway Heights wanted to annex about 1/2 square mile of land, but on the graphic scale, that segment of Airway Heights measures more like 8 or 9 square miles. Moreover, the long runway at Spokane International is about 15 to 20 miles long. You could land the entire Shuttle fleet there and not have a collision!

Unless that little graphical scale should have said "1" where the "5" was. That's probably it ...

Actually, that's the only flaw this great little map has, which makes it so much more unfortunate that it's there. But you know how it is that, sometimes, you can be looking at everything and it all looks so right that you look right past the glaring error? I'm betting that's what happened here.

You can never have too many eyes looking at a thing, but stuff will happen.

Technorati Tags: , , , ,


Isaac Laquedem said...

The scale is probably intended to run from 0 to .5 miles -- half a mile -- instead of 5 miles. The long parallel streets should be 1/2 mile or 1 mile apart, because they'd be laid out on Jefferson's rectangular survey system based on the Willamette Meridian. If the scale bar is 1/2 mile long, then the longer runway would be about 6000-7000 feet long, which seems about right. If the scale bar is 1 mile long, then the longer runway is longer than the longest runway at PDX.

Samuel John Klein Portlandiensis said...

Well-analyzed, Isaac. Ockham's Razor suggests that leaving the decimal point off a ".5" is a much more likely error to make than typing a 5 where you meant a 1, so excellent reasoning there.

Your logic is equally impeccable, and your reasoning from the Jeffersonian PLSS is ironclad. My mistake was thinking the selected roads were 1-mile apart, which I could have checked in Google maps, but I was being lazy and eyeballing everything.

You know what I wonder? How you can take a map like that and figure out the area contained within the irregular figure. I know they probably just total up the areas in the records, but I'll bet there's a way to take that figure and crunch some numbers and come up with the answer.

That's one of my quests, to find this out ...