“For their project, ‘DeLIMITations,’ the artists placed 47 steel obelisks along the route of the 1821 border, from the coast of Oregon to the Gulf of Mexico, stopping in Medicine Bow, Wyo.; Dodge City, Kan.; Waurika, Okla.; and many other towns. Before this undertaking, the 1821 border had never been formally surveyed in its entirety.”