Population Survey Day

What Is Population Survey Day?

Every January 29th is "Population Survey Day" (人口調査記念日, Jinkō Chōsa Kinenbi) in Japan. On January 29, 1872, Japan conducted its first nationwide population survey — creating the "Jinshin Koseki" (壬申戸籍), the first comprehensive national register of Japan's entire population. The survey, based on household registration records compiled across the country, was part of the Meiji government's fundamental project of knowing its population — a prerequisite for taxation, military conscription, and the administration of a modern state.

The Jinshin Koseki of 1872

The Jinshin Koseki (named after the traditional year designation for 1872) required all households in Japan to register with their local government, providing information on household composition, ages, occupations, and addresses. The resulting records were the first attempt to systematically count and categorize Japan's entire population — estimated at approximately 33 million at the time. The survey revealed the composition of Meiji Japan's social structure and provided the government with data essential for planning the new modern state's policies.

From Household Registration to Modern Census

The Jinshin Koseki was not a modern census in the statistical sense — it was a household registration system rather than a survey — but it established the principle of systematic population documentation that led to Japan's first true national census in 1920. Japan's current census (国勢調査, kokusei chōsa) is conducted every five years and is among the world's most comprehensive, providing detailed demographic data that informs government planning across all policy areas.

Japan's Household Registration System

Japan's current household registration system (戸籍, koseki) — a direct descendant of the 1872 Jinshin Koseki — records the legal family relationships of all Japanese citizens. The koseki registers births, deaths, marriages, divorces, and adoptions, and serves as the fundamental legal record of personal status in Japan. Every Japanese citizen has a koseki record, and major life events require official koseki documentation.

Fun Facts

• Population milestone: Japan's population, estimated at 33 million in the 1872 survey, had grown to 126 million at its peak (around 2008) before beginning to decline due to low birth rates and minimal immigration — a demographic trajectory with profound implications for Japan's economic and social future.
• Jinshin Koseki accessibility: The Jinshin Koseki records were sealed from public access in 1968 due to concerns about their use for discriminatory purposes (they recorded former caste status) — making them a complicated historical legacy of the 1872 survey.