New York is to launch an emergency alert system by the end of the year that will send messages to mobile phones during disasters.
Mayor Michael Bloomberg made the announcement at a news conference overlooking the World Trade Centre site.
He said the new technology will give the public clear and accurate information about imminent safety threats.
The mayor said it will be geographically targeted and send messages to all mobile phone users.
The alert plan was approved by Congress in 2006 under the Warning Alert and Response Network Act.
The system also will be launched in Washington by the end of the year.