The U.S. population more than doubled from 1950 to 2016; during that time, the number of vehicles in operation increased by six times and total vehicle-miles traveled grew by seven times. The number of vehicles and vehicle travel began a short decline in 2008 and 2009, respectively, but have grown to new highs in recent years. Growth in licensed drivers has not kept the pace with the growth of vehicle miles traveled reflecting that the average driver drove more miles in 2016 than in 1950. Changing land use patterns and expanding roadway networks have contributed to this trend.
Source: Oak Ridge National Laboratory, Transportation Energy Data Book: Edition 36, December 2017.