If it seems as if commercial architecture has been stagnant for a while, you might be right. For most of the 20th century, styles changed every 10 years or so, rolling through the big cities first, ending up on main street later.

The baby boomer generation saw the biggest changes. In the immediate postwar era, downtowns were characterized by old brick buildings with some classical details, but from the 1950s onward, everything built was modern and simplified. The boomers also were familiar with the exuberant kitsch and button-down corporate modernism of the 1950s and ’60s, the mirrored glass facades of the 1970s and the post-modern classical shapes of the 1980s.

The zoomers — a generation born between 1997 to 2012 — grew up with those styles, as well, but they weren’t there to see them new. They were the existing order, a fait accompli, just like the prewar buildings had been for the boomers. It was someone else’s streetscape. Of course, they know what the IDS Center is, but they have no memory of the sunset poking through the girders while it was under construction, or watching the excavation for the Metrodome.

So it goes with every generational shift. Nothing new there. What makes the boomers different is that the smaller details, the interesting characters, the ordinary commercial architecture of their era, are vanishing rapidly, and they’re the only ones who remember them.

Here’s a sampling of familiar streetscape characters that boomers might recall, while zoomers might find them utterly baffling.

Ask a boomer what they were, and you’ll have a prompt answer. The outdoor kiosks were the little yellow huts, the size of toll booths, usually found in parking lots. One could drop film to be processed into photos there, and pick up the prints later. Fotomats started to appear in the late 1960s, and disappeared in the late ’80s — competition from in-store labs and the rise of digital film did them in. The buildings with oversized roofs stuck around for years, and repurposed, until the lot was reused for housing. That was the fate of the Fotomat in Dinkytown at 4th Street and 15th Avenue SE. Some were just removed because they were empty and impeded traffic.

Ask a zoomer about one, and you’ll get blank looks and shrugs.

The entire baby boomer generation will have to pass from this Earth before people stop lamenting the loss of the Weatherball. It stood atop the Northwestern National Bank Building from 1949 until it was toppled by fire in the great Thanksgiving Day blaze in 1982. Today, it has been gone longer than it was around.