The world is full of strange borders (like Baarle-Hertog and Baarle Nassau), but the one between Derby Line, Vermont and Stanstead, Quebec is both simple and ludicrous:
“In the two-sided town of Derby Line/Stanstead there are two streets that cross the line without any checkpoints. Technically, any time anyone crosses the international line, they are subject to having to report, in person, to a port of entry inspection station for the country they are entering. This makes traffic on the streets that cross the line without a checkpoint, Maple Street/Rue Ball and Pelow Hill/Rue Lee, fairly light, as it is more convenient to cross at Main Street/Rue Dufferin, where checkpoints are often set up for ‘drive thru’ service.
“Pedestrians on the sidewalk are also technically required to report as soon as they cross the line. Visiting someone on the other side of the line, even if the building is next door, means walking around to the inspection station first, or risk being an outlaw. Playing catch on Maple Street/Rue Ball would be an international event, and would break no laws presumably, so long as each time the ball was caught, the recipient marched over to customs to declare the ball.”