User blog comment:StarkBlack/Most Powerful Province?/@comment-9062114-20131018202842

Black Marsh I think is definitely one of them. The Summerset Isles is also in a pretty powerful positions, being the capital of the Aldmeri Dominion, they basically control Tamriel (with Hammerfell and Black Marsh being exceptions of course). If the Stormcloaks win Skyrim would probably become a superpower, if they make the alliance of Tamriel against the Dominion. For now, I would say the most powerful provinces and Black Marsh and the Summerset Isles.