Does the following sentence have an antecedent? If so, where?: Go check out the warehouse. That is where they usually keep the packages.
Both "warehouse" and "where" are nouns and adverbs. Antecedence means something ( usually a noun) has indicated previously by a pronoun.
You are confused or over smart that makes you to ask the question, great!
By Webster dictionary --"where" a single word is never be a pronoun except
adverb, conjunction, noun by functioning in a sentence.
So, how do we infer that it is a pronoun?
Solution is implied by WHERE as it is not in a same sentence too. Antecedence should be in a same sentence or it could not be explicit sometime.
More? Please follow the language portal of Canadian govt. I noticed once they explained it nicely.