This is Zavikon Island, one (or actually two) of the Thousand Islands between New York and Ontario in the St. Lawrence River. You may have seen this picture, with the bridge with flags attached, and the story that the larger island is in Canada and the smaller island is in the United States, causing the homeowner to become an international traveler when visiting his/her other island. That’s not true. According to Wikipedia,
The smaller and more southeasterly of the pair of islands is sometimes called Little Zavikon Island. It has a US-Canada Boundary Commission reference monument, from which, along with other reference monuments on the shore and islands, surveying measurement are used to calculate the international boundary line turning points in the waterway (in this case, about 140 meters southsoutheast of the southern tip of Little Zavikon Island as shown on the largest scale USGS map of the area.
Google Maps shows that the border does not run between the islands. Reportedly, tour guides still beef up their patter with the tale of the island divided by an international border, which is believable because of the flags decorating the bridge. But what a lovely place! You can see a larger version of this picture at Wikipedia. -via reddit
(Image credit: Malcolm Clark)