Mark Dellbringge, you ask a very good question. As Kingsbury & Waterman are both municipal streets (and I can find no evidence, using Sanborn Maps throughout the years, that they were ever MO highways), the only thing I can postulate is that since these bridges were built during the Depression years, that maybe since federal funding, funneled through the state, paid for their construction, possibly that's why the state got credit for their construction. ???