Map Day (First Step Day)

What Is Map Day?

Every April 19th is "Map Day" (地図の日, Chizu no Hi) in Japan, also known as "First Step Day" (最初の一歩の日). On the 19th day of the intercalary fourth month of Kansei 12 (June 11, 1800, in the modern calendar), the surveyor Ino Tadataka (伊能忠敬, 1745–1818) set out from Edo (present-day Tokyo) to survey Ezo (present-day Hokkaido) — the beginning of what would become Japan's first full-scale map based on actual surveys. The day keeps the date as written in the old calendar. His "first step" initiated a project of more than sixteen years that would transform Japan's knowledge of its own shape.

The Remarkable Life of Ino Tadataka

Ino Tadataka did not begin his career as a cartographer. He spent the first half of his life running a sake brewing business in Sawara (now Katori City, Chiba Prefecture). After retiring, at around 50 he became a student of the astronomer Takahashi Yoshitoki in Edo. Energized by a passion for astronomy, calendar science, and surveying, Ino embarked on his first survey of Ezo at 55. He conducted ten survey expeditions over the following years, walking an estimated 35,000 kilometers — the basis of the title of Inoue Hisashi's novel "The Man of Forty Million Steps."

The Map That Amazed the World

Ino Tadataka died in 1818 before his great map could be completed; his students finished it and presented it to the Shogunate in 1821. The resulting "Ino Map" (伊能図, Inōzu) consists of 214 large-scale sheets, 8 medium-scale sheets, and 3 small-scale sheets. Ino mainly used the traverse method — measuring distance and direction from point to point — checked by taking bearings to common landmarks, along with astronomical observations; he did not use the triangulation then common in the West. There is a well-known story that a British survey ship in the 1860s saw a copy of the Ino Map and abandoned its own survey of the coast, impressed by its precision.

The Legacy of Ino Tadataka

Ino's map gave Japan, for the first time, a survey-based picture of its own shape. The maps were used in the Meiji era, for example when compiling national maps, until they were replaced by maps based on triangulation. Ino Tadataka's story is celebrated in Japan as an example of perseverance, curiosity, and taking on new challenges at any age.

Fun Facts

• Ino's hometown: Ino's former residence in Sawara, Katori City, has been preserved, and the Ino Tadataka Museum stands nearby. A statue of Ino stands in Sawara Park, and another at Tomioka Hachimangu Shrine in Tokyo, where he prayed before each survey.
• Lost and found: The official set of large-scale sheets presented to the Shogunate was lost in a fire at the Imperial Palace in 1873, but in 2001 copies of 207 sheets were found at the U.S. Library of Congress, and the whole map can now be reconstructed.
• National Treasure: In 2010, 2,345 items including maps, surveying instruments, and documents handed down in the Ino family were designated a National Treasure as the "Ino Tadataka-related materials."