The little yellow boxes are only as powerful as their low-watt blinking lights, but they hold enormous sway over the masses on street corners all over the planet: When the devices give their marching orders, people march.
And they don't stop moving until signaled to do so.
This month those boxes, the "WALK/DON'T WALK" signs that have become the real movers and stoppers of society, are marking their 50th anniversary on New York street corners - their place of birth, so far as anyone can confirm.
With tens of thousands of them in use, more pedestrians look up to them than to any other object in the urban landscape, threatening clouds possibly excluded.
But for bearers of what should be the clearest of messages - walk or don't - the signals have had a remarkably confused and complicated existence and a constantly evolving design, all aimed at helping people understand when it's time to move and when it's time not to.
Their lighted messages have gone from "WAIT" to "DON'T WALK" to a red palm that means "HANG ON THERE, BUDDY," and even to audible signals that chirp like birds - and still, designers are working to make them more understandable.
Matter of uncertainty
"The problem is what we call the dilemma zone," explains Andy Keel, president of Ron Goodin and Associates, a company that manufactures the signals in Richmond, Va.
"People see the sign blinking, and they get in this big dilemma: 'Do I walk?' 'Does it mean the WALK sign is about to come on?' They're not sure what to do."
For the record, here are the rules: If you're not yet in the street and the "DON'T WALK" sign or its symbolic equivalent, the red palm, begins blinking, you should stay on the corner.
The blinking is a warning to those in the street that they had better slap it in gear because the cars pointed at them are about to get a green light.
Simple enough - but maybe not quite.
Cities in Virginia, Pennsylvania and Ohio, among other states, are testing a new generation of pedestrian signals that seek to remove guesswork altogether.
In the new version, the "WALK" and "DON'T WALK" words or symbols are still present, but they're accompanied by a little clock, counting down the seconds pedestrians have to cross the street.
Aside from forever destroying a punch line - Drunk to wife: "Pick me up at the corner of Walk and Don't Walk" - there are serious problems with the countdown signals, says John Birch, a signal engineer in Austin, Texas.
The problem, as he sees it, is the vanity of the American pedestrian.
Guaranteed: Some guy who thinks he can run the way he did 30 years ago and thinks his new charcoal-black toupee is an anti-aging device will see five seconds remaining on the clock, convince himself he can do a sprint worthy of the Olympics and dash into the street just in time to be smacked by a bus.
"They're a lawsuit waiting to happen," Birch says of the clock signals. "I'd rather people just be told to walk or stay put."
(He swears, by the way, that contrary to all pedestrian skepticism, the little buttons placed on poles to change the DON'T WALK signal to WALK are hooked up to something. They are not, he insists, merely props.)
The challenges for traffic engineers go beyond making pedestrians understand how much time they have remaining to walk - or run, as the case might be.
First, they grapple with just how much time to allot pedestrians before letting the cars rip.
The reasons all boil down to safety. In 1997, the last year full statistics were available, more than 5,300 pedestrians died after being struck by vehicles in the United States.
To reduce the risks, all manner of studies have been completed on pedestrians, their traffic patterns, the speed of their gait, their tendencies to cross against lights and what time of day they're most likely to get injured.
(Answer to the latter: From 6 p.m. to 9 p.m., which roughly coincides with evening rush hour and the end of happy hour.)
Robert Seyfried, director of transportation engineering for the Northwestern University Center for Public Safety, says the data have done little to solve the most serious disagreements in the world of foot traffic.
"Pedestrian signalization is a real controversial area at the moment," he says. "There are serious disagreements about audible signals for blind pedestrians.
"And it's a profession wrestling with what kind of walking speed to use when timing the lights."
Speed and symbols
The vast majority of pedestrians, it turns out, walk about 4 feet per second.
But some need more time in the crosswalks because they walk more slowly, and some walk much more slowly; and it is not unheard of for a chicken to cross the road.
"There are a lot of factors to consider when timing the signals," Seyfried says, "and a lot of disagreements."
In the early 1970s, the government decided symbols rather than words could be helpful, and so the little walking man was born, as was the red palm.
They are supposed to be universal symbols, and they are, more or less. But there are differences around the world.
The Argentina walking man is pudgy.
The Canadians have dressed their walking man in shoes, while most of the others around the world go without.
In Beijing, home to 1 million bicycles, the walking man is supplemented with lighted two-wheelers.
Israel and many Latin American countries use a stationary man as their "DON'T WALK" rather than the upheld hand.
The New York Times covered the installation of that city's first lights on Page 1, explaining in great detail just what the flashing signals meant, that the letters were 4 1/2 inches high (they are now 6 to 9 inches), that they were synchronized to the automobile traffic light and operated on a 90-second cycle.
"For anyone caught in the middle of the street," the Times advised, "pedestrian refuges' have been provided where crossers should wait until it is safe to continue the crossing."
Eight of 10 pedestrians, the reporter observed, obeyed the signs.
The other two, apparently, didn't understand them.