SEATTLE (AP) - High-security driver's licenses aimed at letting U.S. citizens return from Canada without a passport could be adopted elsewhere if Washington state's experiment works, Homeland Security Secretary Michael Chertoff said Friday.

The experiment, signed into law by Gov. Chris Gregoire and formally approved by Chertoff on Friday, calls for Washington to begin issuing new "enhanced" driver's licenses in January.

They will look much like conventional driver's licenses, but will be loaded with proof of citizenship and other information that can be easily scanned at the border.

Radio frequency ID chips and other advanced security features also would make the enhanced licenses less vulnerable to forgery. At about $40, they also would be less expensive than a $97 passport.

Chertoff's endorsement of the pilot project comes as border states prepare for new federal security requirements mandating a passport for travelers - including U.S. citizens - who enter the country by sea or land from elsewhere in the Western Hemisphere.

That requirement is expected to take effect between early 2008 and mid-2009; a similar rule for air travelers already is in force.

Washington state officials are particularly sensitive to the new rule because of the extensive tourist traffic between the state and neighboring British Columbia, home of the 2010 Winter Olympics in Vancouver.

Chertoff praised the enhanced driver's license project, and said he expects other border states to follow Washington's lead.

"I'm quite sure other states that want to use the same technology and the same approach will be welcome to do so," he told a news conference. "The whole idea here is giving a series of alternatives, as long as they meet the same basic standards."