Set of 6 antique mid 19th century lithograph on paper botanical book plate. Published by the US Pacific Railroad Exploration and Surveys 47th and 49th parallel. Unframed, age toning, scattered small spots. The U.S. Pacific Railroad Surveys (USPRR) were a massive 1853–1855 congressional initiative by the U.S. Army Corps of Topographical Engineers to determine the best route for a transcontinental railroad. The surveys spanned multiple latitudes.