There's a time and a place for everything.
Today we’ll be looking at two constructions that are correct, but which one you choose depends on your audience.
“In Which” Versus “Where”
The expressions that concern us today are “which” and “where.” We’ll be comparing sentences like these: “This is the store at which I met my friend” and “This is the store where I met my friend.” As you can probably guess, “which” is more formal than “where.”
In the two sentences about the store, the words “which” and “where” both function as relative pronouns. Relative pronouns, such as “who” and “that,” introduce dependent clauses (1). So in the sentence “The dog that I adopted needed its shots,” the clause “that I adopted” is a dependent clause headed up by the relative pronoun “that.” The relative pronouns “which” and “where” specifically describe place.
When to Use “Which”
If you wanted to discuss where you adopted the puppy, you might say, “The pound at which I found Spot was on State Street.” That’s a pretty formal-sounding sentence, though. You might say that sentence in a courtroom or in another formal situation.
Other than maintaining formality, there are two valid reasons you might want to use “which” instead of “where.” Many times, you can add a preposition before the relative pronoun “which” to make your sentence quite precise (2). For example, “The house at which I saw you” has a slightly different meaning from “The house in which I saw you.” If you use “where,” you lose the subtle distinction: “The house where I saw you.”