I see as late as the 19561939? Minnesota MUTCD (as well as the 1942 federal MUTCD) specified square/non-diamond "caution-type" signs as well as the more familiar diamond "slow-type" signs:
(https://farm3.staticflickr.com/2885/10255750503_aae30bafb5_z.jpg) (https://flic.kr/p/gCgpjx)
Manual on Uniform Traffic Control Devices, Minnesota (https://flic.kr/p/gCgpjx) by afiler (https://www.flickr.com/people/99909734@N00/), on Flickr
I thought I'd only ever seen one of these, in western North Dakota:
(https://farm4.staticflickr.com/3627/3645179644_8cf74dfa84_z.jpg) (https://flic.kr/p/6y7uUU)
Extremely old road sign (https://flic.kr/p/6y7uUU) by afiler (https://www.flickr.com/people/99909734@N00/), on Flickr
Today I realized that I might have photographed a second one of these. It does have a modern font, and could be interpreted as a supplemental plaque rather than a square caution-type sign, so I can't really be sure. (And it looks like it might have previously placed below the SLOW as if it were a supplemental plaque, judging by the yellow patch at the bottom of the sign.)
(https://farm2.staticflickr.com/1386/1100984994_07aa053688_z.jpg) (https://flic.kr/p/2FhQtU)
Norman, North Dakota (https://flic.kr/p/2FhQtU) by afiler (https://www.flickr.com/people/99909734@N00/), on Flickr
Quote from: afiler on November 24, 2014, 01:24:04 AM
Today I realized that I might have photographed a second one of these. It does have a modern font, and could be interpreted as a supplemental plaque rather than a square caution-type sign, so I can't really be sure. (And it looks like it might have previously placed below the SLOW as if it were a supplemental plaque, judging by the yellow patch at the bottom of the sign.)
(https://farm2.staticflickr.com/1386/1100984994_07aa053688_z.jpg) (https://flic.kr/p/2FhQtU)
Norman, North Dakota (https://flic.kr/p/2FhQtU) by afiler (https://www.flickr.com/people/99909734@N00/), on Flickr
Where?
wow, cateyes being specified as late as 1956 in Minnesota? dang. especially that Minnesota is home of the Minnesota Mining and Manufacturing Company, now known as 3M, who was cranking out reflective sheeting as early as 1938.
to answer the question, I've seen quite a few "caution type" signs with text. New York comes to mind most prevalently. they date to the 30s. a side street to US-20 somewhere has a DEAD END with a seven-spot glass reflector in it, even.
I don't recall ever seeing one with a graphic (for an intersection or whatnot).
Gah, you want me to remember where I've seen these? I've seen 'em.
(https://www.aaroads.com/forum/proxy.php?request=http%3A%2F%2Fwww.alpsroads.net%2Froads%2Fnj%2Fnj_62%2Fnbus.jpg&hash=475a3b1f45dfdcaede87584c02807283523de4ab)
Quote from: jeffandnicole on November 24, 2014, 12:47:02 PM
Where?
Norman, North Dakota, roughly here (https://maps.google.com/maps?q=46.659278,-96.940475&hl=en&ll=46.659326,-96.939873&spn=0.003472,0.00545&num=1&t=h&z=18).
Quote from: agentsteel53 on November 24, 2014, 07:19:23 PM
wow, cateyes being specified as late as 1956 in Minnesota? dang. especially that Minnesota is home of the Minnesota Mining and Manufacturing Company, now known as 3M, who was cranking out reflective sheeting as early as 1938.
This is making me doubt my notes now. I'll bet the image is from the 1939 MN MUTCD. I see the library I got it from has 1939 and 1956 MN MUTCDs, so I'll bet I've got the wrong date.
The Pennsylvania Turnpike used to have white-on-green panels reading "CAUTION CURVES" at a few points between Breezewood and New Stanton.