County Route 12 runs west to east along the Babylon Branch of the Long Island Rail Road from the intersection of CR 1 and Old Sunrise Highway (unsigned NY 900D) to unsigned CR 96 at the village of Babylon line in West Babylon.
County Route 12 runs west to east along Oak Street, Hoffman Avenue and Railroad Avenue, parallel to the Babylon Branch of the Long Island Rail Road. It begins at an intersection of CR 1 and Old Sunrise Highway (unsigned NY 900D) and ends at CR 96 at the village of Babylon line in West Babylon.