EA has released a new SimCity developer diary showing off multi-city play, a feature the publisher dubs "one of the crowning achievements" in the game.
"With multi-city play, you no longer need to provide all the required city infrastructures in one city," it explains.
"Build a police station and share your growing police force with the greater region. Have your friend build a fire station in a neighbouring city and soon you'll see their fire trucks putting out flames in your city."
EA has confirmed a SimCity release date of March 8, 2013.