PA 858 begins at an intersection with PA 706 in the Rush Township community of Rushville. The highway begins its long trek in Susquehanna County by progressing northward in a patch of forests. PA 858, which runs west of a creek, is sparsely populated and homes are rare. PA 858 winds its way in and out of forests, heading on a northeast direction. Soon after, there is an intersection with Keefs Hill Road, a locally maintained highway. After Keefs Hill Road, PA 858 heads back into a dense patch of trees. In the forest, is an intersection with C. Warner Road, and soon after comes one for Shadduck Road. Although the dense forest ends, trees continue to surround the highway. The route turns a short drift off its alignment at an intersection with Miller Road. The route turns from the northward direction it was heading to a northwestern direction and intersects eventually with Guilton Road. The dense forestry returns, and Route 858 begins winding its way along. Residential homes have all but disappeared from the route, with trees showing the way into Middletown Center. PA 858 passes a pond to the east, intersecting with the former alignment of PA 859, now a locally maintained highway known as Vet Davis Road and Camp Corby Road. After leaving Middletown Center, PA 858 continues northward and sometimes northeastward. After Middletown Center, PA 858 is surrounded by nothing but trees. There is a break inthe trees when PA 858 intersects with an unnamed road, which serves as a connector to Township Road 768. The state traffic route continues to the northwest, intersecting with Township Road 687. As PA 858 continues, it enters Apolacon Township, where the dense forestry begins to break, and homes begin to show the way. After a short pond is passed, the highway enters Little Meadows. At Maple Avenue, PA 858 runs on its final stretch, passing homes all the way to the New Yorkstate line. There, PA 858 ends and becomes County Route 41 upon entering Tioga County, New York.
History
PA 858 was first assigned in the mass numbering of state traffic routes in Pennsylvania in 1928. However, the southern terminus of the highway was not an intersection with Pennsylvania Route 706. Instead, it was an intersection with PA 67. When it was assigned, it only ran from U.S. Route 106 to Town House Road, since the rest had not been completed yet. The final, already paved segment of SR 858 was completed by the next year. In 1932, the route south of Town House Road was paved. In 1972, PA 67 was decommissioned, and the route at the southern terminus became PA 706.
