of 189,000 kilograms. However, the start of the Pacific War the following year had a great impact on its business. The factory was placed under government control by the National Mobilization Law with Katakura continuing the manage operations; however, its production was shifted to focus on munitions-related materials for aircraft or military use. The number of workers were drastically reduced due to the need for women to till fields as so many man had been conscripted by the army. Exports, which had been the mainstay of the mill since its creation, fell to zero. After the end of the war, the mill was returned to civilian control, and it has escaped damage from air raids. From 1952, automatic reeling machines were gradually introduced and the factory was electrified. Machinery continued to be upgraded over the years and production reached 373,401 kilograms in 1974, the highest it ever reached. However, due to changes in society and the economy, the company faced increased economic pressures. The popularity of synthetic fibers, the decline in popularity of wearing the kimono in everyday use, and the normalization of diplomatic relations with China in 1972 leading to an increase in the imports of cheaper Chinese silk led to the company stopping production on February 26, 1987. The closing ceremony for the plant was held on March 5, 1987. World Heritage Site After the factory was closed, the Katakura company continued to maintain the buildings at considerable expense for many years.The mayor of Tomioka City and the governor of Gunma Prefecture expressed an interest in preserving the site and promoting it to UNESCO as a World Heritage Site, and Katakura agreed to sell the site to Tomioka city for a nominal value in 2005. The site was designated as a National Historic Site the same year. The oldest buildings were designated Important Cultural Properties in 2006. Three of these buildings were designated a National Treasure in 2014. The site was listed on Japan's World Heritage Tentative List as "Tomioka Silk Mill and Silk Industry Heritage Group" on January 30, 2007. The formal nomination was accepted by the World Heritage Center on January 31, 2013, and it was officially registered at the 38th World Heritage Committee on June 21, 2014. Gallery The Important Cultural Property designation collectively covered seven buildings, including one iron water tank and one sewage ditch. The National Treasure designation covers three buildings: the reeling