The Bethpage State Parkway begins at Southern State Parkway exit 31, a trumpet interchange located within the Massapequa Preserve in the hamlet of North Massapequa. On the southbound Bethpage Parkway, the junction is signed as exit B1. From the Southern State Parkway, the Bethpage proceeds northward through North Massapequa and the town of Oyster Bay as a two-lane highway, traversing the northwesternmost part of the Massapequa Preserve. The forests of the preserve serve as a buffer between the highway and the dense neighborhoods of North Massapequa, and this setup follows the parkway to exit B2, a northbound-only exit for Boundary Avenue. Heading northbound, the stretch prior to the exit gore is two lanes wide.