The exact number of cars on the road in the US in 2018 is not known, as there is no central database that tracks this information. However, according to the Federal Highway Administration (FHWA), there were an estimated 276 million registered vehicles in the US in 2018. This number includes cars, trucks, buses, and motorcycles.
The number of cars on the road has been increasing steadily over the past few decades. In 1960, there were only about 60 million registered vehicles in the US. By 2000, that number had grown to over 220 million. The increase in the number of cars on the road is due to a number of factors, including population growth, economic growth, and the increasing popularity of driving.