I am extremely poor in Geography and I regret for being so, too. I got to know of this piece of information from a little extra googling after watching "Who wants to be a Millionaire?" show.
Well, the fact is that at a closest space, US and Russia are only 2.5 miles apart. We can imagine to go to tomorrow and get back to yesterday if there are no Cross-Border issues; how sweet!!
The distance between Little Diomede, an Island in Alaska, USA and the Big Diomede, an Island belonging to Russia is just 2.5 miles. The two islands are situated within the U.S.-Russian maritime border. During winter, when the water body (Bering Strait) surrounding the area freezes, it is possible to walk between the two islands – from America to Russia and vice versa. And we can juggle between today and tomorrow or today and yesterday.