Independent truckers across the United States began pulling their rigs off the road at midnight to protest increased fuel and road-use taxes, but faced possible confrontations with other drivers who vowed to keep working.
Still others said they weren't sure whether to keep driving or not.
"All we get is hearsay," said Kyle Hayden of Baton Rouge, La. "There's not any major organizing going around."
There were no confirmed incidents of violence. Business was reported slower than usual at some truck stops in Indiana, South Carolina, Pennsylvania and Connecticut.
Independent truckers, who haul most of America's fresh food and much of its household goods and steel, own and operate their own rigs and belong to many different truckers' groups.
No nationwide agreement was reached on a strike deadline. David Kolman, a spokesman for the Independent Truckers Association in Los Angeles, had said the walkout would begin at 12:01 a.m. EST today, but truckers in Ohio and Massachusetts, for example, said their deadline was 12:01 a.m. EST Tuesday.
Mike Parkhurst, president of the ITA, said early today that independent drivers were heading home but added it may take several days for the strike to "jell."
The Independent Truckers Association represents 30,000 truckers, according to Parkhurst, but other trucking groups dispute that figure.
Many independent truckers said they intended to keep off the roads for fear of violence against non-strikers.
In Pennsylvania, Teamsters organized "SWAT teams" to keep their trucks rolling and warned strikers not to stop them.