The first stop sign installed in Detroit is generally dated to 1915.
Detroit’s early sign was created by police sergeant Harold “Harry” Jackson, who was stationed at a difficult intersection where poor visibility made traffic control especially demanding. He fashioned a sign from plywood, cut off its corners, wrote “STOP” across it, and positioned it to control traffic entering from the troublesome street.
Some historical accounts date Jackson’s first handmade sign or experiment to 1914, while official highway-history summaries commonly record the first Detroit stop-sign use as 1915. The quiz answer follows that widely cited installation date. The original design looked nothing like the modern red octagon: early U.S. stop signs used black lettering on a light background and were smaller.
National standardization came later. In 1922, a committee supported by the American Association of State Highway Officials selected the octagonal shape because it remained recognizable from the back. The familiar red-and-white design was standardized nationally in 1954.