I found the following information about this location on this web site:
From the second torii to the Shrine, there is an elevated walkpath called Dankazura, roughly 50 centimeters high, 3 meters wide and 460 meters long, lined with some 310 cherry trees and azaleas on both sides. In early April, the path turns long arch made of cherry blossoms. Cherry seedlings were planted in 1918. Its botanical name is Prunus Yedoenis, same as those near the Potomac River in Washington D.C., which were the gift to the American First Lady Mrs. Taft presented by the Governor of Tokyo in 1912.