All photographs are abandonings. Once there was a moment, the click of a shutter, and now it's gone, a framed ghost, abandoned by time and failing memory. This is the sentiment at the heart of photography's mechanical mystery.

In Maxwell MacKenzie's gigantic black-and-white landscapes, however, the moment in question isn't just the moment the shutter clicked, but a moment that slipped by decades or even a century before, when something went wrong and a farm began to edge toward ruin.

MacKenzie is a native of western Minnesota and he has driven uncountable thousands of miles across the West to photograph these ruins before they're all gone -- leaning barns and windowless houses jutting up like wreckage in oceans of furrowed wheat and sorghum, architecture that looks more like a visible absence of something, like a missing tooth, than it looks like a presence of sun-curled clapboard and tatters of tar paper. It looks like ruins, in other words, relics of dreams that didn't work out.

America has decay but it's short on ruins. How odd that MacKenzie would find ruins in Minnesota, South Dakota, Montana and Idaho, out where there's nothing between you and Siberia but a barbed wire fence, as they say.

These pictures continue a theme MacKenzie has been exploring since he studied photography at Bennington College in the 1970s. He's a commercial photographer now, specializing in architecture, but when business gets slow, he heads for his home country and searches out what's left of a pioneer belief that it was possible to become Jefferson's yeoman farmer.

What's there now is mostly industrial farming, with its air-conditioned tractors with subwoofer sound systems, and huge metal sheds. But lingering amid the terrible economic truths of modern farming, MacKenzie will find an abandoned homestead. He shoots it with a Fuji Panorama camera and enlarges it with technology that produces prints up to eight feet long, prints so big he just pins them to the walls at the American Institute of Architects, unmatted and unframed.

In most of the 23 pieces in "Abandonings West," the building stands in the middle of the picture. Surrounding it is land, lots of land, with an armada of clouds above, proceeding through a sky often rendered black by the red and polarized filters he uses to control the strangeness of his infrared film.

Something about infrared film makes pictures feel like thoughts, a little spooky, as if the camera has recorded something going on inside your head and projected it onto a wall.

In a picture titled "Near Fish Lake, Otter Tail County, Minnesota," the white trees stand like wonderfully artificial 18th-century renderings of leaves hinting at bowers beneath, shelter from the prairie winds and the relentless horizon. Up a small hill stands a ruined house. You wonder what moment began its long decline. A leg broke, prices fell, an angel of the Lord appeared in flames and said, Go thou from this land.

The panoramic pictures themselves have the answer: the land. There's so much land, so little house. Everything is tiny here, including you. You're at the mercy of land and weather that are merciless. In the woods of the settled East, it's possible to imagine spirits and ghosts watching you, but the Great Plains don't care any more about you than the ocean does. They aren't dangerous as much as they're unforgiving. Pioneers may have thought: If I do everything right I'll be fine.

Wall text argues otherwise, quoting from memoirs and books about boredom, bad luck, debt, despair; about the blizzard that leaves you burning your inside walls to stay alive because if you go outside for firewood you'll vanish; about a summer erupting with wheat until the grasshoppers darken the sky and eat everything -- wheat, vegetable garden, even the leaves on the trees; about a husband who tells his wife he'll be right back after he rides out to round up two cows -- she watches him ride around the cows and keep going and he never comes back.

Every year now, country fire departments torch these ruins for practice sessions. Wheat and sorghum farmers fill the cellar holes and run their furrows over them. The abandonment itself is erased. MacKenzie is preserving not only the collapse of dreams, but also the architecture that arose to express them.

These buildings were cheap, balloon-frame things, put up quickly so that farmers could work on their plowing. They have a rectilinear naivete, a defiant quality insisting that 90-degree angles and plumb bobs will show the prairie who's boss.

We've had no shortage of photographers making pictures of barns in glorious, weathered color. MacKenzie used to work in color, though panorama gave his stuff an edge that wouldn't quite work on a bank calendar. Then he wondered how abandonings would look in black-and-white, and after a lot of experiments, he settled on the infrared film.

These pictures put you between nature and society, dreams and ruins, something and nothing. How American, except that they show ruins.

For so long we envied Europe its ruins. We studied paintings of Corinthian columns peeking from the rubble of lost cities where peasants and goats frolicked in a poignancy that verged on the smug. (Poignancy is what we had before irony.) We recited Shelley's "Ozymandias," about the folly of belief in architectural immortality, but we admired the Europeans' acceptance of their ruins, of the risings and fallings of civilizations as part of life and nature.

We admire Europe's sophistication, we condemn its decadence. We've tried to find what the Founding Fathers called a "middle ground" of the agrarian ideal between wilderness and civilization. Hard as we've tried to make it work with everything from homesteading to a Teddy Roosevelt investigation of the collapse of small towns to the back-to-the-land movement of the '60s and '70s, the dream keeps eluding us, maybe even betraying us. Hardly anyone lives on a farm anymore -- about one in a hundred Americans.

Back when more than half did, some of them lived in the houses that MacKenzie photographs, driven by the hopes that he captures along with the architecture.

Abandonings West, photographs of the Dakotas, Idaho, Montana and Minnesota by Maxwell MacKenzie, is on exhibit on the first and second floors of the American Institute of Architects, 1735 New York Ave. NW. The building is open 8:30 a.m. to 5 p.m., Monday through Friday. Admission is free.