The Texas birth index from 1956 gives a county number of
057 for a birth record I found, how can you determine what county that corresponds to, and more generally, how can I map any county number in Texas vital statistic records to its name?
I think the answer is Dallas County, but I'm having trouble finding an official Texas document that defines these county code numbers. I checked page one of the Microfiche, but no legend was there, it just starts in immediately with the index to the records.
The index is found on Ancestry.com and cites as:
Source Information Ancestry.com. Texas Birth Index, 1903-1997 [database on-line]. Provo, UT, USA: Ancestry.com Operations Inc, 2005. Original data: Texas Birth Index, 1903-1997. Texas: Texas Department of State Health Services. Microfiche. Description This database is an index to over 15 million births recorded in the State of Texas, USA, between 1903 and 1997. Information available in this index includes: child's name, sex, birth date, and birth county. Some records may also include: names of both parents.
Here is an image of the index record: