Route 540 (Halewili Road) is a state highway that stretches from Route 50 in Eleele back to Route 50 in Kalaheo on the island of Kauaûi.
The road is mainly an alternative to Route 50 and for the first , the Pacific Ocean is in view as the highway travels easterly. Route 540 then takes a sharp turn north at the Kauaûi Coffee plant, towards Kalaheo. Numerous agriculture fields surround the road.