In Florida a notable non-giant one I remember is because the river is a location which had historically been the legal borderline between different counties. O

In Florida a notable non-giant one I remember is because the river is a location which had historically been the legal borderline between different counties. One county north of the river, the adjacent county existing south of the river. The island itself, not specifically within either county technically. Oral history of Rum Island in the Santa Fe river goes back to the time when liquor was prohibited by US law, and regardless of whether local officials knew about it, they could honestly testify that there was no remaining liquor within their jurisdiction.