The Federal Highway Administration reports that travel on U.S. roadways through the first eight months of 2011 has reached its lowest level since 2003.

The period through August of this year shows a 1.3 percent drop from the same time last year. The numbers continue a growing trend of diminished driving, falling 1.7 percent or 4.6 billion miles traveled.

Of all states, South Dakota saw the biggest decline in driving, with a 5.8 percent drop. The figures reflect an overall drop in rural driving, with a 2.7 percent decline, compared to a 0.5 percent drop in urban travel. Regionally, the northeast saw the biggest drop in car use with 2.2 percent. 

The figures could reflect the nationwide ballooning of the average price of gas, which for the month of August was nearly $1 higher per gallon than the same period in 2010, according to the Energy Information Administration.