Identify the subordinate conjunction in this sentence, Laura Ingalls Wilder didn't write a book about her pioneers experiences until she was in her 60's

Subordinating conjunction is a word which connects words or group of words as in the case of dependent and independent clauses in complex sentences.

T he subordinating conjunction in the sentence above based on the definition is until she was in her 60's.

In this example, until serves as an indicator at the beginning of the conjunction.