Another stretch of homes north of Purchase leads to Westchester County Airport, situated between NY 120 and the New York–Connecticut state line about to the east. Here, I-684 begins to run alongside NY 120 as both roads pass by Rye Lake, an offshoot of the Kensico Reservoir. NY 120 widens to four lanes ahead of the airport's main entrance in the town of North Castle, where the road connects to I-684 via Airport Road (unsigned County Route 135 or CR 135).