Across the county line in the town of Vestal, NY 434 assumes the name Vestal Parkway and heads into more densely populated areas that serve as Binghamton's suburbs. The homes alongside the road are replaced by businesses in the hamlet of Vestal, the first of several large communities that NY 434 serves in Broome County's progressively widening river valley. It becomes a major commercial strip as it proceeds northeastward through the community, a trait that NY 434 retains throughout the Binghamton suburbs. Just east of Vestal's central business direct, the highway intersects NY 26 at a partial cloverleaf interchange just south of NY 26's full cloverleaf with NY 17. Past NY 26, the Southern Tier Expressway heads across the Susquehanna River, leaving NY 434 as the primary highway on the river's south bank.