BISMARCK, N.D. (AP) — Lawrence Welk didn't have a flush toilet where he grew up, but visitors to his childhood home in rural North Dakota now do.

Science informs us that our sense of smell can evoke vivid memories. The phenomenon is sometimes known as the “Proust Effect,” for a scene from Marcel Proust’s novel “Remembrance of Things Past,” when a character’s childhood memories come flooding back, triggered by the scent of a sweet cake called a madeleine.

In cities across the U.S., the housing crisis has reached a breaking point. Rents are skyrocketing, homelessness is rising and working-class neighborhoods are threatened by displacement.

These challenges might feel unprecedented. But they echo a moment more than half a century ago.