I know you're probably looking for current information, not out of date, but in case it helps: I believe Arctic wolves were held at Milwaukee County Zoo in the recent past. I think they switched to timber wolves for some time before they went out of wolves entirely, but I may be incorrect.
I think Brookfield was once misreported as holding Arctic wolves when they held Northern timber wolves. They switched to Mexican gray wolves in 2003 with a single northern wolf persisting for a year or so after the Mexican gray wolves joined the zoo.
In general, Arctic and northern wolves have been phased out a lot in favor of the Mexican gray wolf and red wolf programs, since they are highly endangered, especially since many zoos only have space for one wolf exhibit and some have gone out entirely. (Milwaukee, Denver)