September 15, 2021 — So many modern conveniences have become so commonplace that we take them for granted, often not realizing the great benefits derived from new gadgets and technologies. One of the foundations of traffic safety, “stop-and-go” lights, provides better flows of cars and trucks on the streets of North Dakota cities and towns.

This day in history was a red-letter one for Minot, for on this day in 1939, city workers installed a new overhead traffic signal. The signal, located at Second Street and Fourth Avenue South, was to be an experiment to see if drivers could navigate through the intersection better with a mechanical monitor. The “site was selected due to the large number of accidents” that had “occurred at the corner in the past,” according to Minot city manager J.W. Bliss. The Minot Daily News gave clear directions as to how the lights would work: “the unit has three signals. They are stop, with a red light; caution, amber; and go, green.”

Some years before, Minot had put an earlier signal right smack dab in an intersection, in the pavement, but it had to be removed because it had been “struck by passing cars” far too often. If this new overhead light proved satisfactory, then other signals, according to the local newspaper, might be purchased for use on “Main Street and [at] other busy intersections.” The trial period was for thirty days, until mid-October of 1939. Policemen on foot stood nearby and gave local drivers a few days to “get used to the device,” and violators who got confused by the colored signals were not arrested.

While obedience to red and green lights seems simple to modern minds, the city of Minot had to add new laws for motorists in order to make the experiment successful. The city council ruled that pedestrians also had to “observe the stop-and-go signal light.” Another rule clearly stated that “no traffic may enter the intersection while the red light is lighted, and all pedestrians and vehicles shall proceed into and thru the intersection when the green light is lighted.”

Police were lenient for four days, but then police chief W. E. Slaybaugh laid down the law. “In the future,” he said, “those persons disregarding” the light “may expect to be arrested.” Slaybaugh clarified that even “bicycles . . . must “observe the lights.” Finally, the city put up new signs near the intersection to warn drivers of the traffic signal.

Did the experiment work? Yes. Drivers responded in a “satisfactory” manner and Minot officials gave the “green light” for funding to install five more traffic lights after the month-long experiment ended in mid-October of 1939. The new signals were in place before Christmas of that year.

“Dakota Datebook” is a radio series from Prairie Public in partnership with the State Historical Society of North Dakota and with funding from the North Dakota Humanities Council. See all the Dakota Datebooks at, subscribe to the “Dakota Datebook” podcast, or buy the Dakota Datebook book at

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