Here is a list of WooCommerce country code and state code data. This data was extracted directly from the WooCommerce plugin and therefore, can be used for tax rate classes and maybe other WooCommerce related plugins that may require a state code or country code.
Note that while the help text mentions that we should use “2 digit state codes”, I have found that some countries have states codes that are longer than 2 digits. I have tested tax rates for Peru with the 3 letter state code “PAS” and it worked.
I believe that my tax calculations wouldn’t worked without that 3 letter code. While my test passed, I still recommend testing such codes prior to using them on a production site just to be sure.