Thanks for this magnificent link. I had already been using http://www.astro.com as one source for determining latitude/longitude for cities. But I had no idea that you could actually use it as a timezone converter, even for historic times, and indeed implements the Shanks & Pottenger database. I have been following your advice and wandered around to find possible boundaries of timezones. In the "Beijing" area I have not found any deviations, but I have also not pushed it far. So Asia/Shanghai seems to cover the regions Hebei, Shandong, Fujian, Jingxi, Guangdong, Hunan, Hubei, Anhui, Henan, Shanxi, Zhejiang, Jiangsu and Liaoning. All are on GMT+8 in 1970. In Qinghai there was a zone on GMT+7 with Haiyan, Gonghe, Tongren, Jigzhi, Xining, and another zone on GMT+6 with Yushi, Zhidoi, Qumalai, Nangqen, Delingha, Golmud, Lenghu and Mangya. In Tibet (Xizang) there was a zone on GMT+6 with Lhasa, Chamdo, Shigaise, Jimsar, Shawan and Hutubi. Another zone on GMT+5 with Pulan, Aheqi, Shufu, Shule . On GMT+7 there were also the regions Shaanxi, Nei Mongol and Hainan. In Gansu it seems the vast majority of the area was on GMT+7 right up until its westernmost part, where I found a single city Dunhuang on GMT+6. I'm sure there most be more cities in this area on GMT+6 but I haven't got around to check it. The cities on GMT+7 were Lanzhou, Linxia, Tianshui, Pingliang, Wuwei, Zhangye, and Yumen. My major effort has been on the Xinjiang area, which has a lot of counties, so it is not easy to determine a map. The cities on GMT+5 were Aksu, Atushi, Yining, Hetian, Cele, Luopu, Nileke, Zhaosu, Tekesi, Gongliu, Chabuchaer, Huocheng, Bole, Pishan, Suiding, Yarkand. The cities on GMT+6 were Urumqi, Turpan, Karamay, Korla, Minfeng, Jinghe, Wusu, Qiemo, Xinyan, Wulanwusu, Jinghe, Yumin, Tacheng, Tuoli, Emin, Shihezi, Changji, Yanqi, Heshuo, Tuokexun, Tulufan, Shanshan, Hami, Fukang, Kuitun, Kumukuli, Miquan, Qitai and Turfan. The cities in Xinjiang I could find lies in the upper and lower part of the region, while there is a central zone where I could not find any cities that coincided with astro.com, but this might also be because it is a big desert area. Many counties have a name that corresponds to the city name also, so I could often find it that way, but not for the following counties: Awati 40.11 80.57 Shaya 40.53 81.43 Kuche 41.77 83.51 Xinhe 41.34 82.13 Baicheng 42.07 81.97 Wensu 41.59 80.38 Wushi 41.20 79.13 Luntai 41.70 84.65 Yuli 40.83 87.00 Hejing 42.88 85.32 The coordinates above correspond to the approximate center of the county. I'm looking for cities near these county centers that would lie inside the county and exist in www.astro.com to produce a GMT offset for 1970. Can anyone help? Unfortunately there is apparently no "show nearby cities" or map in astro.com, so it is a bit of guesswork. The amount of different spelling for each name is also amazing, but perhaps not if you consider "anglified name", yughur, pinyin, traditional chinese, kazakh and uzbekh as valid variations, probably flavored with a nice collection of typos too. Regards, - Jesper Paul Eggert writes: -----Original Message----- From: Paul Eggert [mailto:eggert@cs.ucla.edu] Sent: Martes, 27 de Junio de 2006 12:05 To: Jesper Norgaard Welen Cc: tz@lecserver.nci.nih.gov Subject: Re: Chinese timezones For that sort of thing the Shanks & Pottenger database is the best that I know of, though of course it's not infallible. They do attempt to cover the wartime changes. Shanks was born during Eastern War Time and notes this fact in the author's bio on his book. You should be able to determine the zone boundaries yourself, if you have good maps, by consulting the Atlas Query <http://www.astro.com/cgi/aq.cgi>, which is an online version of the Shanks & Pottenger database. For example, I just verified that according to that database, Harbin was at UTC+0830 on 1970-01-01 00:00. As far as I know, the only post 1970 change in China was in May 1980, so if you use any time stamp from 1970 to 1980 you should be able to wander around the Chinese countryside using that database and determine where the time zone boundaries were. (Good luck with the spellings, though!)