Most roads have them—unless you're venturing off into unpaved territory: the line markings running down the center.
Now, anyone who drives knows what they're for: keeping traffic even and safe, of course. But how did they get there? File this one under those questions that you find yourself pondering on hour nine of your summer road trip.
The first white line road marking dates back to 1918 in the United Kingdom, according to Traffic Signs and Meanings. This idea caught on quickly, but the markings weren't recognized as road safety protocol until 1926.
In the '30s, the lines were used for much more than telling you how much road you have to work with. In a time when traffic lights didn't exist, solid white lines served as stop signs and other cautionary signals, often manned by policemen to help direct traffic.
Yellow lines, meanwhile, didn't make an appearance until the 1950s, according to Traffic Signs and Meanings. At this time, the two colors were simultaneously used on roads—with white directing traffic heading in the same direction and yellow used for two-way roads or traffic.
In 1956, dashed lines entered the scene, bringing with them a whole new set of rules for overcoming other cars on the road.
The first lined road in the United States was Trenton's River Road in Wayne County, Michigan, which dates back to 1911. Edward Hines, at the time the chairman of the Wayne County Board of Roads, came up with the idea after watching a leaky milk truck make its way down the road, according to the Michigan Department of Transportation. Hines was posthumously inducted into the Michigan Transportation Hall of Honor for the idea in 1972.
Another fun fact: Those dashed lines you see on the road are much longer than you'd think. When you're driving, it's easy to mentally mark these as a couple of feet long. However, as per government guidelines, the dashes are 10 feet in length.
Erika Owen is the Senior Audience Engagement Editor at Travel + Leisure. Follow her on Twitter and Instagram at @erikaraeowen.