Cigarette butts are the single biggest trash item found along highways in Texas, a study found, with hundreds of millions discarded on roadways in the state each year, the Associated Press reported June 24.

Texas drivers tossed an estimated 400 million butts onto the roads in 2009, according to the Texas Department of Transportation's Visible Litter Study. The study found that 43 percent of all roadside trash was tobacco-related; nonalcoholic drink containers comprised 13 percent of litter, followed by household items at 9 percent.

The study found less food-related garbage along state roads but about 33 percent more trash overall — an estimated 1.1 billion pieces — an increase attributed largely to tobacco trash.