Upon crossing into Greene County, NY 42 is in the town of Lexington. Residences become more sporadic as NY 42 continues northward through Lexington, crossing under the power lines before bending northward through the dense woods of Halcott Mountain and Deep Notch, soon bending northeast into a large field area, where it enters the hamlet of West Kill. In West Kill, NY 42 intersects with the western terminus of CR 6 (Spruceton Road). NY 42 through West Kill consists of several residences along both sides of the highway before crossing over the namesake kill and bending northwest out of the hamlet. While running east of West Kill, NY 42 remains a two-lane residential roadway, crossing over the waterway once again and intersecting with Beechridge Road North.