Examples and Observations:
- "It must be wonderful to live in a safe and timeless place, where you know everyone and everyone knows you, and you can all count on each other."
(Bill Bryson, The Lost Continent. Harper & Row, 1989)
- This Hollywood restaurant is one of the quintessential power spots, especially on Mondays, when stars abound and tourists are discouraged.
- "The reason why so many wealthy Americans come to Europe is to avoid this obligation to work."
(Alexis de Tocqueville, Democracy in America, 1840)
- The relative adverbs where, when, and why also introduce adjectival clauses, modifiers of nouns denoting place (where clauses), time (when clauses), and of the noun reason (why clauses):
Newsworthy events rarely happen in the small town where I lived as a child,(Martha Kolln, Rhetorical Grammar: Grammatical Choices, Rhetorical Effects. Pearson, 2007)
We will all feel nervous until next Tuesday, when results of the auditions will be posted.
I understand the reason why Margo got the lead.
- "The relative adverbs where, when, and why are exemplified [below] in -. Of these citations,  is non-restrictive and - are restrictive:
 A similar scenario occurs around the margins of the Amazon basin, where farmers are forced to encroach onto the forest margins in order to subsist. [W1A-013-62]The relative adverbs can be replaced by relative pronouns or by prepositional phrases with relative pronouns as complements."
 We hear little of the day-to-day successes but only of the odd occasion when conflict arises [S2B-031-53].
 But that was one reason why I never wanted to do that again actually [S1A=008-63]
(Sidney Greenbaum, Oxford English Grammar. Oxford Univ. Press, 1996)
- "She smoked in the bathtub, where we'd find her drowned butts lined up in a neat row beside the shampoo bottle."
(David Sedaris, "Diary of a Smoker." Barrel Fever. Back Bay Books, 1994)
- "Oh, give me a home where the buffalo roam
Where the deer and the antelope play;
Where seldom is heard a discouraging word,
And the sky is not cloudy all day."
(Brewster Higley, "Home on the Range")
- The reason why worry kills more people than work is that more people worry than work.
- "But when the place where she played became too well known, she began to sing with an accompanist, became a star, moved to a larger place, then downtown, and is now in Hollywood."
(Langston Hughes, The Big Sea, 1940)
- "A line of people filed through the parlor where, among lace whirligigs, Jack's coffin rested on black-draped sawhorses."
(E. Annie Proulx, The Shipping News. Simon & Schuster, 1993)
- "Like relative pronouns, relative adverbs introduce relative clauses.
- "The relative adverb when is used to modify a noun phrase of time. Such noun phrases include nouns that denote periods of time such as, day, week, hour, minute, month, year, and similar events.". . . The relative pronouns that or on + which can be substituted for the relative adverb when. . . .
- The relative adverb where is used to modify a noun phrase of place, location, or space.
- The relative adverb why is used to modify a noun phrase with the noun reason
"The relative pronouns which and that can be substituted for the relative adverb where. When which or that is used, a preposition of place must be included."
(Andrea DeCapua, Grammar for Teachers: A Guide to American English for Native and Non-Native Speakers. Springer, 2008)
- Relative Adverb Clauses
"Relative adverb clauses are subject and predicate (finite verb) structures carrying out the grammatical functions attributed to an adverb modifier. They are introduced by the relative adverbs when, where, and why, expressing such meanings as time, place, and reason. They differ from relative adjective clauses only with regard to the grammatical functions that the pronouns carry out within their own clauses. Similarly, these relatives carry out the grammatical function of connector. As sentence constituents they both modify or refer back to an antecedent in the independent clause, which is a noun or its replacement."
(Bernard O'Dwyer, Modern English Structures: Form, Function, And Position, 2nd ed. Broadview Press, 2006)
- "The relative adverb where begins a clause that modifies a noun of place. For example, 'My family now lives in the town where my grandfather used to be sheriff.' The relative pronoun where modifies the verb used to be, but the entire clause modifies the noun town.
"A when clause modifies nouns of time. For example, 'My favorite day of the week is Friday, when the weekend is about to begin.'
"A why clause modifies the noun reason. For example, 'Do you know the reason why school is out today?' Sometimes the relative adverb is left out of these clauses, and the writer substitutes that instead. For example, 'Do you know the reason that school is out today?'"
(James Stroman et al., Administrative Assistant's and Secretary's Handbook. Amacom, 2004)