Thomas Wade and Herbert Giles devised their romanization system in 1867, drawing upon earlier systems used by missionaries. Many classical works of sinology written since then have made use of the Wade-Giles system, and it is generally the system of choice in Taiwan, but other systems are also used here. These include: (1) a system developed by the Qing dynasty's postal service in 1906 for communications with overseas postal authorities; (2) Gwoyeu Romatzyh, developed by Zhao Yuanren in 1928; and (3) the Yale system, developed in 1948 for teaching Chinese at the university level. The Yale system was once used extensively throughout the world in Chinese instruction.
In 1958, the PRC government announced the adoption of Hanyu Pinyin, a system that had been 20 years in the making. The government there worked to promote acceptance of its system, which was eventually certified by the International Standards Organization. The United Nations adopted Hanyu Pinyin in 1986 as its official romanization system. Many overseas libraries, museums, and educational organizations then followed suit, and Hanyu Pinyin has since become the most widely accepted system around the world.
More recently, ethnologist Yu Bor-chuan has spearheaded the effort to develop Tongyong Pinyin, which is basically a modified version of Hanyu Pinyin. Yu, a researcher at Academia Sinica's Institute of Ethnology, touts his system as being compatible with Hanyu Pinyin while providing for the romanization of Taiwanese and Hakka as well. When Chen Shui-bian was mayor of Taipei, the city government elected to switch the city's street signs to Tongyong Pinyin in order to preserve historical place names and show proper regard for language as it is actually spoken by the locals. The same step has also been taken by a few townships in Ilan county. Disconcertingly, the romanization of Taipei's street signs has become a hodge-podge of Wade-Giles, Tongyong Pinyin, and the Hanyu Pinyin favored by current mayor Ma Ying-jeou, who sees adoption of Hanyu Pinyin as a means of making the city more international.