No, you're not hallucinating as you travel. These enigmatic structures are dotted across the length and breadth of the United States, they were built in the late 1920s and early 1930s to help guide pilots navigating the country's fledgling air mail system in an era long before satellites and GPS.Back in the day, the arrows were illuminated by neighboring beacons. Now, most of these light towers are long gone and the arrows lie abandoned -- some visible on Google's aerial maps.For those in the know, tracking these strange formations can be a compelling pastime. Retired Californian couple Brian and Charlotte Smith drive around the United States, snapping photographs of the arrows for their specialist website Arrows Across America.The Smiths discovered the indicators almost by accident after Brian, a former police officer with the California Highway Patrol, was sent an email about them. The couple was immediately intrigued."Charlotte got really interested in it and wanted to find what it was, so started researching, looking for them on the internet," Brian tells CNN Travel.
She found little to go on."What sparks my attraction to the arrows was that this existed and I had no clue about it, and there was no information about it," says Charlotte, a former genealogy researcher.She's right, there's really not much information available online. Contrary to popular belief, the arrows have no association with the US Post Office.
