The Old Chain of Rocks Bridge over the Mississippi River from Madison, Illinois, to St. Louis Missouri, has, with the completion of a newer Chain of Rocks bridge in 1999, been strictly a pedestrian bridge and bikeway. The span, built in 1929 with an unusual curve hard to decipher from a distance, is remembered with fondness as the connector carrying historic U.S. highway 66 from its origins in Illinois into Missouri. Photo by Carol Highsmith, 2021.