Middle Island

Middle Island is the southernmost point in Canada, located at 41°41'N, 82°41'W, which is about 41.7 degrees north latitude. It lies in Lake Erie, just south of Pelee Island, which is more well-known as it is a popular vacation destination.
Middle Island is uninhabited by humans, as it has been set aside by the Canadian government as a bird sanctuary. The most common species there are cormorants, though several others also nest there. It once was the site of a lighthouse. Despite its lying in Canadian waters, for many years the island was privately owned by various Americans.
The island is further south than even Boston and Detroit - or Rome, Italy, and 27 U.S. states extend further north than this outpost of "the Great White North", including 11 which are entirely to its north (Maine, New Hampshire, Vermont, Wisconsin, Minnesota, South Dakota, North Dakota, Montana, Idaho, Oregon, Washington, and Alaska).