The 85% Speed Limit Rule: An Outdated Policy Jeopardizing American Road Safety

For decades, the United States has relied on a nearly century-old formula—the so-called “85th percentile rule”—to set speed limits on roads across the nation. This rule dictates that the posted speed should match the speed at or below which 85% of vehicles travel in free-flowing traffic. While this may seem grounded in data, it actually institutionalizes the dangerous idea that speeding is normal and acceptable if most drivers do it.Take Mitchaw Road in Sylvania Township, Ohio. Here, residents like 85-year-old Rose Hammond have pleaded with authorities to reduce the speed limit below its current 55 mph owing to frequent speeding...