The odometer is an instrument that measures the distance that a vehicle has traveled. Although every single car is manufactured with one of these instruments, few people know much about them. That’s why we recommend everyone take a few moments to observe National Odometer Day on May 12th every year and learn more about these amazing devices. After all, there are over 1.4 billion cars in the world today, and the vast majority have working odometers installed in them.

The History of Odometers

According to many historians, the first odometer was created by the Roman engineer and architect Vitruvius in 15 BCE. This odometer was a standard-size chariot wheel that turned 400 times during a Roman mile. It was mounted in a frame with a cogwheel. For every mile the chariot traveled, the cogwheel would engage a gear and drop a pebble into a box. The operator could then count the pebbles in the box to find out how far they had traveled. Historians disagree, however, as to whether this odometer was actually used in day-to-day life.

During the 17th century, Blaise Pascal invented a rudimentary odometer called the Pascaline. This device had gears and wheels. Each gear contained approximately 10 teeth that, when advanced one complete revolution, would advance a second gear. This is the principle that mechanical odometers have used for years. Also invented during the 17th century was an odometer for ships that was created by Thomas Savery—an English engineer and inventor who patented the first crude steam engine by the end of the century.

Mormon pioneers crossing the plains on the journey from Missouri to Utah also invented a rudimentary odometer in 1847. This odometer was called the roadometer and was attached to a wagon wheel. This device counted the revolutions of the wheel as the wagon moved forward. It was designed by Orson Pratt and William Clayton and was built by carpenter Appleton Milo Harmon.

Around the turn of the 20th century, Charles and Arthur Warner introduced their patented Auto-Meter. This odometer used a magnet and a rotating shaft to induce a magnetic pull upon a thin metal disk. Measuring this pull allowed the device to provide measurements of both speed and distance in one instrument. In 1912, the Warners sold their company to the Stewart & Clark Company of Chicago. The company would be renamed the Stewart-Warner Corp, and by 1925, they were making odometers and trip meters for automobiles. Most of the cars and motorcycles manufactured in the U.S. during this time were equipped with one of these odometers. By 2003, most vehicles stopped using mechanical odometers as digital ones became more popular.

Observing National Odometer Day

Anyone wishing to observe this holiday can do so by learning more about the odometer. Odometers not only allow us to keep track of the distance we’ve traveled but they also help us to place a value on our vehicles since the number of miles on the odometer affects the purchase price of the vehicle. While observing this holiday, be sure to use the hashtag #NationalOdometerDay to spread the word about it.