I WAS HERE (National Road nr Greenup IL)
This replica one-lane wooden bridge is a popular spot for a very old tradition. Whatever the legal status, it's bound to happen.
Mid-19th Century pioneers along the California, Oregon and Mormon Trails did much the same thing--carving names, dates and messages into Independence Rock in Wyoming. While some, including Native Americans, may have seen it as an act of desecration then, today it's a National Historic Landmark.