Is 'where' used as a pronoun in relative clauses?

Question

Please take a look at the following examples:

1. (a) Statement: He works in a office.
   (b) Relative clause:
   　　1. The office where he works (is for rent).
   　　2. The office in which he works (is for rent).

   Here, 'where' = 'in which', and I think 'where' is used as an adverb to mean 'in, on, at or to which' in relative clauses.

2. (a) Statement: He works near the office.
   (b) Relative clause: The office near where he works.

   I think here 'where' = 'the office'.

My questions:

1. Is 'where' used as a pronoun? (as 2.(b))

2. Can we use other prepositions of places (except 'in, on, at, to') with 'where' as 2.(b)?

   For example:

   　　1. The bridge under where we live...
   　　2. The beach behind where i am standing...
   　　3. The shop next to (close to/before/opposite/in front of, etc.) where we live

Answer 1

Where is a ‘pro-form’—it ‘stands for’ or refers to another entity in the discourse—but it is not a pronoun. It should be understood as a ‘pro-adverbial: it stands for an adverb, or for a clause or preposition phrase which acts as an adverb.

Because where does not stand for a noun or noun phrase, it cannot act as the object of a preposition:

^∗ The office in where I work is on the fourth floor.

If you want to refer to the place itself in a preposition phrase you must use which:

^ok The office in which I work is on the fourth floor.

HOWEVER: this does not mean that the three examples in your question are ungrammatical; they are grammatical, but they do not mean what you want them to mean.

Just like pronoun wh- forms, where can be used to head an interrogative:

Where do you work? —I work at 1801 Broadway.

Where can also head a bound relative clause:

I work at 1801 Broadway, where my office is on the fourth floor.

Here where is equivalent to in or at which place.

• Note, by the way, that in such clauses where may also have the extended sense of at the place where:
  

  I work on Broadway, where it intersects with Washington.

Where can also be used to head a fused relative clause; and this is where it gets tricky. In this sort of clause the wh- form does not stand for another entity but designates a ‘variable’ whose referent is not specified: in effect, the wh- form is its own referent! A fused relative clause acts as an NP (nominal); for instance, it may be the subject or object of a verb:

Where I work is my office on Broadway.
I will tell him where I work, and he can meet me there.

And the clause—not where itself, but the entire clause it heads—may also act as the object of a preposition:

The bus stops three blocks from where I work.

That is what is involved in your three examples. As you will see from the paraphrases, they signify something quite different from what you intend:

1. The bridge under where we live... This does not mean that you live under the bridge, but that the bridge is under the place where you live: apparently you live over the bridge! What you mean is The bridge under which we live ...
2. The beach behind where I am standing... This does not mean that you are standing behind the beach, but that the beach is behind the place where you are standing: apparently you are standing in the water looking out to sea! What you mean is The beach behind which I am standing...
3. The shop {next to/close to/before/opposite/in front of, etc} where we live... These are not all so absurd as the previous examples, because the spatial relationships are in most cases reciprocal: if the place where you live is ‘opposite’ the shop, the shop is also ‘opposite’ the place where you live. Still, before and in front of inverts the spatial relationship; and in all these cases, you are inverting your topic: instead of a bound relative clause describing where you live relative to the shop, you have a fused relative clause describing where the shop is, relative to where you live.

• NOTE: It is true that in casual speech (and in writing which reflects casual speech) where often ends up with the sense of a pronoun; Man_From_India cites

  Where's your favorite destination?

  In speech, people often start sentences pointing in one direction, and then end them somewhere else. That’s ordinary and inevitable, because they’re assembling their thoughts on the fly. Hearers allow for that imprecision because they’re parsing the same way; and as long as the rough sense is clear nobody worries much about the syntactic details. Noncasual writing, however, demands strict precision, because there’s no opportunity for the writer and reader to clear up any ambiguity or misunderstanding which may arise. My answer above addresses the precise use of where in noncasual writing, which would require

  What is your favorite destination?

---

^∗ marks a usage as unacceptable

Answer 2

The reply from StoneyB is genius, but some online dictionaries disagree.

The Cambridge Online English Dictionary says: "We can use 'where' as a relative pronoun: The hotel where we spent our honeymoon has been demolished. The hall where you’re giving your talk has a really good sound system."

Merriam-Webster Online Dictionary has a NOUN definition of where (which would also indicate its ability to be used as a pronoun): "What place, source, or cause. I don't know where that came from."

Dictionary.com also defines 'where' as a pronoun: "What place?: Where did you come from? "The place in which; point at which: This is where the boat docks. That was where the phone rang."

So in my mind, yes, 'where' is sometimes a pronoun, just like the word 'place' can also be a noun.

And in the OP's (2b) sentence, "The office near where he works," the word 'where' isn't modifying a verb; it is referring back to (standing in place of) a place/location, which is a noun.