This is a relatively new trend I've observed in recent years.
I've lived in IL decades ago, nobody started sentences with "I mean" unless they were clarifying what they last said.
People have started doing it here in CA as well, it's not unique to IL and it's not a long-established pattern.
As far as I can tell, it's basically the new "uhhh" people would use to stall as they organize their thoughts. What surprises me is how habitual it has become, to the extent that people now start written sentences with "I mean" when they're not clarifying anything at all.
So* , I grew up in Texas and the "I mean" prefix goes back in my schooling years as far as I can remember. Though it usually is coupled with a bitchy attitude like the rhetorical "You do realize $X, right?"
* I'd say if there's a new one, it's the annoying "So" prefix. Mark Zuckerberg says it a lot. Common on HN as well. And the usage I'm referring to, like "I mean", is when it doesn't call back to anything and could be removed without consequence.
Similar age here, but west chicago suburbs (Naperville). People overused "Like" a lot back then, but I see that today among teens in CA as well but it's more of a valley girl thing. I don't remember "I mean..." lead-ins as being overused, maybe I've just forgotten. Teens aren't exactly known for using language correctly though, I give the kids a pass.
One of my IL buddies moved out here a years ago and has started saying it recently after a starting new startup job he shares with a bunch of millenials. He never used to do it, now half his sentences start with a long drawn out "I meeeaaaaan," and it makes me want to gouge my eyes out whenever we socialize. Grown man in his 40s starting half his sentences with something equivalent to "Uhhhhhhhhhhh", no pass, FML.
I've lived in IL decades ago, nobody started sentences with "I mean" unless they were clarifying what they last said.
People have started doing it here in CA as well, it's not unique to IL and it's not a long-established pattern.
As far as I can tell, it's basically the new "uhhh" people would use to stall as they organize their thoughts. What surprises me is how habitual it has become, to the extent that people now start written sentences with "I mean" when they're not clarifying anything at all.