WASHINGTON

- States should ban all driver use of cellphones and other portable electronic devices, except in emergencies, the National Transportation Safety Board said yesterday.

The recommendation, unanimously agreed to by the five-member board, applies to both hands-free and hand-held phones, and significantly exceeds any existing state laws restricting texting and cellphone use behind the wheel.

The board made the recommendation in connection with a deadly highway pileup in Missouri last year that killed two and injured 38 others. The board said that the initial collision in the accident, near Gray Summit, Mo., had been caused by the inattention of a 19 year-old-pickup driver who sent or received 11 texts in the 11 minutes immediately before the crash.

The pickup, traveling at 55 mph, rammed the back of a tractor truck that had slowed for highway construction. The pickup was rear-ended by a school bus that overrode the smaller vehicle. A second school bus slammed the back of the first bus.

The pickup driver and a 15-year-old student on one of the school buses were killed in the Aug. 5, 2010, accident.

The accident is a "big red flag for all drivers," NTSB chairman Deborah Hersman said at a meeting to determine the cause of the accident and to make safety recommendations.

The NTSB doesn't have the power to impose restrictions, but its recommendations carry significant weight with federal regulators and congressional and state lawmakers.

When the crash occurred, Missouri had a law banning drivers younger than 21 from texting while driving, but it wasn't aggressively enforcing the ban, board member Robert Sumwalt said.

"Without the enforcement," he said, "the laws don't mean a whole lot."