Hawaii County Route 240 is a 9.6-mile highway located on the Hamakua Coast of the Big Island. The highway begins at Hawaii Route 19 near Honokaa and tracks westward to Waipio Valley Road. Hawaii County Route 240 was originally designated as Hawaii Route 24 when the Hawaii Route System was expanded to the Big Island in 1955. The corridor was later renumbered to Hawaii Route 240 during the 1970s and has been recently relinquished to Hawaii County in recent years.
The infamous Waipio Valley Road is a 0.9-mile roadway which spans from the terminus of Hawaii County Route 240 to the floor of Waipio Valley. The roadway is signed with a 25% gradient (seen in the blog cover photo) and sustains an almost nearly 20% grade to the valley floor. Traditionally Waipio Valley Road was open to Four Wheel Drive vehicles and hikers. Access was restricted to Hawaii County residents and registered tour operators in 2022 due to safety concerns over slope slip-outs.
This page is part of the Gribblenation Hawaii Roads series. A compellation of all Hawaii-related media from both Gribblenation and RoadwayWiz can be found by clicking here.
Part 1; the history of Hawaii County Route 240 and Waipio Valley Road
Waipio Valley is the largest and southernmost of seven valleys located on the Hamakua Coast of the Hawaiian Big Island. The valley is located on the windward side of the extinct volcano that is Kohala Mountain. Waipio Valley is thought to have formed approximately 250,000-300,000 years ago following a massive landslide along the northeast slope of Kohala Mountain.
Waipio Valley is one of the most fertile places on the Big Island and was the most prominent population center on the Big Island during the era of ancient Hawaii. Much of the ruling class (Ali'i) of ancient Hawaii resided in the valley which often is called the "Valley of the Kings." Kamehameha I received a statue of his war god Ku in Waipio Valley and was where he was told that he would one day conquer the Hawaiian Islands. Much like Puuhonua O Honaunau the valley was considered a place of refuge for those in violation of Kapu (ancient Hawaii Laws).
Waipio Valley is thought to have had a population of between 4,000-10,000 by the time of arrival of Captain James Cook during 1778. During the 1800s the valley saw an influx of Chinese settlers who began farming rice. Waipio Valley grew large enough that it had many services one would expect in a modern town such as schools, hotels, churches and a post office.
The 1916 United States Geological Survey map of Waipio shows the community connected to Waipio Bay by road and a trail to Kukuhaele. The trail to Kukuhaele more is or less is what now is known as Waipio Valley Road.
A road west of Honokaa to Waipio Valley can be seen on the 1930 Hilo Chamber of Commerce map of the Big Island. It isn't clear when the first automobile reached Waipio Valley via massive incline of Waipio Valley Road.
Much of Hamakua Coast was devastated on April 1, 1946, by a tsunami striking the Big Island. While the tsunami didn't kill anyone in Waipio Valley it completely wiped out all the existing infrastructure within it. This destruction led to a major population decline which would see the valley the residence to only approximately 50 people by modern times.
The 1954 United States Geological Survey map of North Hawaii displays the trail to Kukuhaele widened to highway standards.
In 1955 the Hawaii Route System was expanded to the Big Island. Hawaii Route 24 was designated as a new highway which originated at Hawaii Route 19 near Honokaa. Hawaii Route 24 used Honokaa-Waipio Road, Mamene Street, Honokaa-Waipio Road and Kukuihaele Road to reach Waipio Valley Road.
Hawaii Route 24 and Waipio Valley Road can be seen on the 1959 Gousha Highway map of Hawaii.
Hawaii Route 24 was renumbered to Hawaii Route 240 during the 1970s which denoted it as a secondary corridor. Hawaii Route 240 can be seen on the 1975 United States Geological Survey map of Hawaii.
By the 1990s Hawaii Route 240 bypassed Kukuhaele Road in favor of an extension of Honakaa-Waipio Road towards the Waipio Valley Lookout. This then new alignment is seen on the 19995 United States Geological Survey map of Kukuhaele.
Hawaii Route 240 was relinquished to Hawaii County sometime between 2018-2022 as the corridor no longer appears as part of Hawaii Department of Transportation inventory for the Big Island.
On February 25, 2022, Waipio Valley Road was closed to visitors due to safety concerns related to slope failure. Previously the roadway had been open to Four Wheel Drive vehicles and hikers. After threat of a lawsuit the closure was amended on September 16, 2022, to permit Hawaii County residents and authorized tour companies access to Waipio Valley Road.
Waipio Valley Road is often claimed to be the steepest road in the United States. The posted gradient at the westbound beginning of the 0.9-mile long Waipio Valley Road is 25%. Numerous sources claim the roadway peaks at the gradient of 42-45%. These claims seem to be in error as Pjamm Cycling Inclinometer readings indicate the maximum gradient is 24.6% whereas the average gradient is 19.8%.
Part 2; a drive on Hawaii County Route 240
Westbound Hawaii County Route 240 begins at the outskirts of Honokaa along Honokaa-Waipio Road.
Hawaii County Route 240 passes through Honokaa via Mamane Street and transitions back onto Honokaa-Waipio Road. Honokaa was centered around the Hamakua Sugar Company which operated in the community from 1873 to 1994. Honokaa resembles many of the numerous plantation communities found on the Hawaiian Islands.
Hawaii County Route 240 follows Honokaa-Waipio Road west of Honokaa and intersects the original highway alignment at Kukuihaele Road.
Hawaii County Route 240 ends at Waipio Valley Road and the Waipio Valley Lookout parking lot.
Part 3; Waipio Valley Road and the Waipio Valley Lookout
The westbound beginning of Waipio Valley Road can be seen below. The gradient sign reads 25% and the roadway is staffed with Hawaii County workers to control access. Waipio Valley Road is one of two roadways explicitly prohibited from use by Enterprise Rental Car on the Big Island.
While I couldn't hike Waipio Valley Road the corridor is often featured on YouTube driving videos (Greg Lampert footage linked below). The roadway is approximately one roughly paved lane which has numerous yield points. Traffic is prioritized so downhill traffic yields to traffic coming up from Waipio Valley. Former residents of the Big Island I've spoken to have claimed that older non-fuel injected vehicles often had difficulty with fuel pickup on the uphill climb.
The Waipio Valley Lookout has numerous historical information stations. The view overlooks the 2,000-foot-high cliffs and black sand beach on Waipio Bay.
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