Turn signals are a foundational automotive safety feature. Before their widespread adoption, drivers worldwide relied on hand signals, but these gestures were not standardized across borders. In the early 20th century, mechanical 'trafficators' and early illuminated arrows appeared, yet a uniform system was lacking for decades, with the U.S. only mandating turn signals in 1953.
This lack of standardization meant drivers had to learn hand signals, which differed confusingly between countries. For instance, while the U.S. settled on an upward bent arm for a right turn, the U.K., with right-hand drive, required extending the right arm palm-forward for the same maneuver. Other signals, like slowing down or stopping, also had regional variations.
Although electric blinkers, first used by Buick in 1939, made hand signals largely obsolete, they remain crucial knowledge for cyclists and drivers with malfunctioning lights. Historical records, like the 1931 U.K. highway code, show how these signals evolved, with some countries like Australia still lacking a formal left-turn hand signal. Today, illuminated signals provide needed uniformity, though understanding historical hand signals offers insight into early automotive communication challenges.