Most of the ice storms that happen in the USA happen in the Northeast part of the USA however some Ice Storms have occurred in the Southern part of the USA as well.
I know Kansas, and Arkansas are two states that I've been too where Ice Storms occurred and Arkansas tends to have the most Ice Storms of those two states.
At least that's been my experience since I lived in Arkansas for around 7 years and Ice Storms tended to happen a lot during the winter there with frequent power outages.
I'm sure the ice storms occur a lot in other states as well.
Canada seems to get a lot of Ice Storms too especially in Quebec and even Alberta Canada.