312 was my area code when I was a kid, and I still feel a connection with it. All Chicago phone numbers -- both the city and the suburbs -- were 312 until I entered the double digits, when Chicago kept 312 and 708 became the area code for the suburbs. It remained that way till the truly inglorious and forgettable 847 arrived, and I've stopped developing fond feelings for area codes ever since.
By the way, as for "Chicagoland," I never liked that phrase, but it rolls off the tongue better than "The Greater Chicagoland Area," which I should remember every time I stumble over "Columbia Waterfront District." It seems I'm destined to live in places that push the 140-character limit.