In parts of Ohio and Pennsylvania, it is “Kater-Corner.” They are mostly Republitards there. Go figure.
Thank you for your valuable research! That’s quite interesting 
I have to believe that kittycorner was an intentional play on cattycorner, itself a corruption of catercorner, though probably not intentional. The “cater” part means four as already mentioned, but in caterwaul, it actually does mean cat. And in caterpillar too according to the dictionary I’m looking at. Hmm, interesting.
I grew up saying catty corner. Born and raised in south Texas.
Catt(dd)y Corner. But not in the context of the OP. Only used it to mean things on diagonals from each other. Usually in a group of four.
It was catty-corner where I grew up, except for my buddy’s father who insisted on saying catty-wampus.
My mom always said kitty-cat-corner.
Always “kitty-corner” for me. I never heard “cater-corner” until this thread.
Southern Ontario and southern Alberta here.
I think that was the strip joint down by the intersection.
My mom is 78, and that’s the phrase she uses.
Thank you. But I got a surprise. I dug out my American Heritage Dictionary to check the pronunciation. As expected, they have it as [ˈkætər ˌkɔrnərd]—but right after that they gave an alternative pronunciation: [ˈkætiː], yet with the spelling “cater-”. That was in addition to giving the rest of the spellings “catty” and “kitty” with their respective pronunciations. For those, it just says “also:” without making any judgments.