----------------------------Original message---------------------------- Most US counties lie entirely within a time zone. However, there are a few counties (see below) which span two time zones. Can anyone tell me how to determine the precise transition line (presumably a longitude) which demarcates adjacent time zones for these anomalous counties? Any help (including pointers to appropriate maps) will be appreciated. I have a copy of Will Tefft's Map Link time zone map, but it lacks sufficient detail. State County FIPS Time zones ----- ------ ---- ---------- FL Gulf 12045 -5/-6 ID Idaho 16049 -8/-7 NE Cherry 31031 -6/-7 ND McKenzie 38053 -6/-7 ND Morton 38059 -7/-6 ND Sioux 38085 -7/-6 SD Jones 46075 -6/-7 SD Stanley 46117 -7/-6 P.S. I'll be providing timezones for all US cities in the Geographic Name Service.