I have a list of census blocks for California and I am trying to get the county for each row.
If I have a census block of 60070004024003, which 2 digits make up the county FIPS?
Your example is missing one character (it is 15 in total). In California it should be
060070004024003 (starting with
06; see here).
The first and second digits identify the state. The third, fourth and fifth ones identify the county within the state. So,
06007 gives a unique identifier for a county (source).
Assuming you have a list in a spreadsheet (Excel, for example), column A. Type in B1: