WALNUT CREEK (KGO) -- Brian and Charlotte Smith are as busy as ever these days.
They are on a mission to document and preserve a part of U.S. history most Americans know nothing about.
The Sacramento-area husband and wife team are behind the website Arrows Across America which tracks a network of century-old big concrete arrows that can be seen from the air.
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More than 90 years ago, those markers guided the first pilots across the United States to get mail from one coast to the other. Pilots searched for the arrows from the air and pointed their airplanes in the direction where the visual guides pointed.
Many of the arrows are long gone. A few remain, including one at the ridgeline of Acalanes Ridge in Walnut Creek. Another arrow is located at the Oakland city stables but is not publicly accessible.
The arrows helped pilots navigate transcontinental air mail routes in an era when there were no official aeronautical maps, radar, or GPS.
"They'd have crude maps," Brian Smith said. "They'd make their own and share them."
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Two airmail routes intersected at the Walnut Creek arrow. They originated at Mills Field in San Francisco (the former name of what is now San Francisco International Airport) and at Oakland Airport.
According to the Smiths, one arrowhead pointed towards Concord and the other towards Livermore. The public can hike to the Acalanes Ridge air mail arrow, which over the years, has been popular with graffiti artists.
"These arrows were made for pilots to follow during the daytime," Charlotte Smith said. "They kind of knew where they were going. They flew the route so often that they kind of had landmarks memorized."
The Arrows Across America website documents each site where an arrow was located. The Smiths started researching the arrows in 2013 after one of Brian's former co-workers tipped him off that some of them were still around.
The couple has driven across the country in search of these concrete remnants in what has become a nationwide treasure hunt.
"We've been having a lot of fun with this," Charlotte said. "It's like we're not retired anymore. It's been keeping us young, and you need to do stuff to keep you young."
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