How a national speed limit could improve our lives.

The first automotive speed limit in the United States was enacted in 1901, when the state of Connecticut declared it illegal to drive faster than 12 miles per hour on its highways. The first speeding ticket, one must imagine, followed only shortly thereafter. We freewheeling Americans don’t cotton to the idea of limits, as anyone who has ever tried to actually drive 55 miles per hour on an interstate can attest.

But the latest case for driving the posted speed limit, and lowering that speed limit altogether, is not about safety (though even a rudimentary understanding of physics would support that argument). Rather, it’s about saving money and reducing carbon emissions. A car’s gas mileage peaks at speeds around 40 miles per hour (depending on the car), and then decreases rapidly. This is because air resistance increases exponentially as a car goes faster. At high speeds, a car’s engine is using the majority of its energy simply to overcome that resistance—rather than accelerating—which wastes fuel.

This revelation isn’t new. A 1974 law instituted a national speed limit of 55 miles per hour (a compromise between efficiency and speed). But as the oil crisis abated, the law was amended to 65 miles per hour in 1987 and finally repealed entirely in 1995, ceding the power to set speed limits back to the states. Now, many states have speed limits that exceed 70 miles per hour on interstates, and some stretches in Texas and Utah have limits as high as 80.

Article continues in the GOOD.IS/The Slow Issue