Someone mentioned in another thread that To Kill a Mockingbird is a Great American Novel. I’ll go along that’s it’s one of them. Here’re a few more I’d add
Housekeeping, by Marilyn Robinson
Anything by Mark Twain
The Bell Jar, by Sylvia Plath
Their Eyes were Watching G-d
Catch-22, by Joseph Heller
The Color Purple, by Alice Walker
The Grapes of Wrath, by Steinbeck
The Tattooed Potato (YA fiction, but great anyway), by Ellen Raskin
Franny & Zooey, by JD Salinger
The Bluest Eye, by Toni Morrison
The Handmaid’s Tale, by Margaret Atwood
Washington Square, by Henry James
The Bostonians, by Henry James
The Invisible Man, by Ralph Ellison
Shoeless Joe, by Phil Alden Robinson
Gone with the Wind by Margaret Mitchell
A Gentleman In Moscow, Amor Towles (this is an excellent book to read at this moment, by the way – the story of a Russian aristocrat who is on permanent house arrest in a fancy hotel in Moscow, and how he makes the best of it, a very gentle, witty, but pointed book).
Willa Cather and Marilyn Robinson already mentioned, two of my very favorite novelists.
Eudora Welty: the Golden Apples, the Robber Bridegroom