Rising sharply from the plains of western Nebraska, Scotts Bluff was a critical landmark for 19th-century emigrants traveling the Oregon, California, and Mormon Trails. After weeks of navigating by rivers and rutted tracks, wagon parties would spot this towering formation and know they were on the right path.  Today, from overlooks reached by steep trails or a winding summit road, that same geography still reads clearly: The North Platte River curves through the valley, and faint traces of historic trails remain etched into the earth below.  Each of the two overlooks offers a slightly different perspective. The South Overlook has vistas over the broad sweep of the river valley, where movement and migration defined the terrain. Those who trek up can clearly see four of the five named rock formations of Scotts Bluff: Crown Rock, Dome Rock, Eagle Rock, and Saddle Rock.…