Japan's National Route 339 suddenly turns into 362 stairs, making it the country's only highway that becomes a staircase

At Cape Tappi, on the northern tip of Aomori Prefecture in Japan, a fully official national highway ceases to be a road and becomes a flight of stairs. According to Sotogahama Town's official government website, the section of National Route 339 that crosses the cape consists of 362 steps totaling 338.2 meters, and it is Japan's only national highway with a staircase section, known locally as a 'kaidan kokudo.' It is still legally classified as part of the national highway network, even though no cars, motorcycles, or scooters are allowed anywhere near it.

For many Americans, that idea takes some getting used to. On the interstate system, a highway number always means pavement wide enough for traffic. Route 339 breaks that assumption, and it has done so since Japan's government designated the highway on November 12, 1974, with the designation taking legal effect on April 1, 1975.

Why does a highway have stairs
Route 339 runs through western Aomori Prefecture, passing through municipalities including Itayanagi, Tsuruta, Goshogawara, and Nakadomari on its way to Cape Tappi, the northernmost point of the Tsugaru Peninsula, before continuing on to its official terminus at an intersection with National Route 280 in Sotogahama. Aomori Prefecture's official road division lists this Nakadomari-to-Cape Tappi stretch as part of Route 339's official alignment. For most of its roughly 108.4-kilometer length, it functions like any other numbered route, complete with intersections, connections to prefectural roads, and a link near Goshogawara to the Tsugaru Expressway.

The terrain changes sharply at the cape itself. The land there is steep and tightly packed with housing, leaving little room for a conventional road bed. Rather than reroute the highway around the obstacle, officials left an existing local stairway in place when Route 339 was formally designated and incorporated it into the highway. The National Diet Library's digital archive of Japanese landmarks confirms that this is Japan's only national highway with a staircase section, as the surface here consists of stairs rather than pavement.

According to a popular local story, the stairway was folded into the highway almost by accident, on the theory that whoever approved the route never actually inspected the site in person. That version is folklore, not a documented fact. Sotogahama Town's records indicate that the steep terrain and dense housing made a standard road impractical, so the existing stairs were left in place and later developed into the tourist route seen today.

What it is actually like to climb it
The staircase connects Tappi Fishing Port, near sea level, to the Tappizaki Lighthouse at the top of the cape. At the base, a highway marker in the same style as those on ordinary Japanese roads stands where the pavement ends and the steps begin.

Near the top, a monument features a button that plays a well-known song about the Tsugaru Strait, a detail that has made the climb a popular stop for visitors. The strait itself separates Honshu from Hokkaido, and the staircase overlooks it directly.

One detail matters for anyone planning to visit: the surrounding road network closes for the winter. Aomori Prefecture's official road division lists the Route 339 segment leading to Cape Tappi as generally open from early April through mid-November, with the exact winter closure dates varying year to year depending on snowfall. Check seasonal status before making the trip.

Why a staircase highway is worth paying attention to
For a US audience expecting highway numbers to denote paved roads, Route 339 is a perfect example of how infrastructure takes geography into account. Americans have long engineered highways to cross mountains and bays. In this rare case, the Japanese government has considered the area's extreme geography and population density and allowed the stairs to bear the highway name.

This is a unique addition to how a country that highly depends on cars deals with difficult geography. In most places, roads win. In Cape Tappi, the stairs do.