When the jetliner crashed into the Pentagon on Sept. 11, 2001, emergency responders weren’t sure where they’d find enough radios so that the hundreds of rescuers could talk to each other.

That’s no longer a worry, said Bob Griffin, director of emergency management for Arlington County. The Washington Metropolitan Region has a cache of 1,250 radios, and public safety agencies throughout the area have upgraded their radio systems so that fire officials in Loudoun County can flip a switch and speak with rescuers in the District of Columbia or Montgomery County.