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During our summer vacation in 2003, my wife and I amused ourselves by taking leisurely drives in Ohio and photographing every diamond-shaped highway sign that we saw along the roadsides. (Well, not every sign; only the distinct ones.) For provenance, I also stood at the base of each sign and measured its GPS coordinates.

This turned out to be even more fun than a scavenger hunt, so we filled in some gaps when we returned to California. And we intend to keep adding to this collection as we drive further, although we realize that we may have to venture to New England in order to see `FROST HEAVES'.

All photos on these pages were taken by Jill C. Knuth, unless noted otherwise.

Many of these signs have an official ``MUTCD number'' from the Manual on Uniform Traffic Control Devices of the U.S. Department of Transportation. A nice website discussing them has been put together by Richard C. Moeur, a Professional Traffic Engineer in Phoenix, Arizona. Another good publication with dozens of additional signs is the Pennsylvania Handbook of Approved Signs. My wife and I have encountered many nonstandard signs, documented here, although we have not yet found examples of all the standard ones on Moeur's list.)

We've also collected some noteworthy Canadian examples, as well as a few from Australia, Mexico, and New Zealand.

Our collection is limited to signs that appear in a diamond shape, even though many other interesting signs exist. For example, we don't stop to photograph a sign like or even a rectangular sign that includes an image of a diamond-shaped sign (except this one).

Note: All GPS coordinates on these webpages follow the map datum conventions of WGS 84 (World Geodetic Survey 1984).

These pages were last updated on 22 January 2012; so far we've found and photographed 1150 different signs. (Here's a current list.) Hundreds more are still out there waiting to be catalogued; for example, Christopher Wheeler's Great American Road Sign Project includes many signs from the east that I've never spotted out west.

One we'll probably never see: NO WINTER MAINTANCE

Google Maps

Brian Cornell has set up a great website where you can see where the signs were photographed.

Don Knuth's home page

diamond signs home page

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