An online discussion was sparked after a netizen questioned why the pinyin for the province of "陕西" on a sign inside Shaanxi History Museum was written as "Shaanxi" instead of the expected "Shanxi". 

The museum responded on August 30 to clarify that "Shaanxi" is the official standard spelling. This distinct spelling is used to differentiate the province from its neighbor Shanxi province. Shaanxi, located in inland Northwest China and home to the ancient capital Xi'an, uses the spelling with the double "a".

Why is "山西" spelled as "Shanxi" while "陕西" is spelled as "Shaanxi"?Some experts have pointed out that, to standardize Chinese place names for international use, the Place Name Research Institute of the National Bureau of Surveying and Drawing adopted the tonal spelling rules of "Gwoyeu Romatzyh" while compiling the Hanyu Pinyin edition of the Provincial Atlas of the People's Republic of China. It was under this system that "陕西" was transcribed as "Shaanxi" — a spelling that remains in use today.

Gwoyeu Romatzyh system: A tonal romanization system for Mandarin Chinese developed in the early 20th century.

The Gwoyeu Romatzyh system uses specific spelling conventions to denote tones without diacritics: the first tone is unmarked, the second tone is indicated by adding "r" after the vowel, the third tone by doubling the main vowel, and the fourth tone by adding "h" after the vowel. Accordingly, the character "陕", which carries the third tone, is written as "Shaan" by doubling the vowel "a", hence resulting in the spelling "Shaanxi" for the province.

"Shaanxi" is the state-approved spelling used in specific contexts to distinguish the province from its neighbor "Shanxi". The extra vowel replaces the tone mark that would normally differentiate the two names. This spelling convention is only necessary when tone marks cannot be used.

Currently, both the People's Government of Shaanxi Province and the official website of Shaanxi Daily use the spelling "Shaanxi." This convention is also reflected in public signage beyond the province. For example, South Shaanxi Road (陕西南路) in Shanghai is written as "Shaanxi Rd (S)" on street signs.