A lot is riding on this. It is the Future Farmers of America contest for best market swine, with ten dollars and a ribbon for the winner. For the winner's owner, to be precise. The winner will have a slightly less happy fate.
State fairs are always wonderful events, rich pageants of American life, and the Iowa event is the Louvre of state fairs. Agriculture is not just the main industry here but the very heart of community life for many people.
Flying in, from 20,000 feet up you can see the fields of corn shifting like water as the wind rustles the stalks and the light catches their sinuous movement. The state fair celebrates this richness.
In the agricultural building, where produce is brought to be judged, the stalks of corn are laid out on wire racks all down one wall as reverently as Roman sword handles in the British Museum. There are wooden cases of older, unhybridised corn varieties coloured bright yellow, dark red, pale straw or all colours together, like tiny mosaics.
There are onions as round and smooth as billiard balls. There are huge glossy aubergines, cabbages as big as ten-pin bowling balls, tomatoes as big as pumpkins and pumpkins so large that they threaten to collapse back into themselves.
The butter cow is the heart of the show, a huge milky-smooth animal carved from butter every year for four decades by "Duffy" Lyon. To mark the anniversary, this year she has also carved The Last Supper from butter, a vast tableau that sits in a chiller cabinet next to the cow.
The point where Iowans and agriculture interact most intensively is at the food stand. There are hundreds of them selling more than you can imagine in your greediest dreams.
The most emblematic of Iowa is the corn dog - a hot dog dipped in a heavy cornmeal batter, then deep fried in hot oil - even though it was imported from Texas.
It is all delightfully innocent. You can sit on the grass and eat your corn dog while little railway cars chug and clang around the fairground, listening to the Humboldt Community Chorus sing old favourites by Creedence Clearwater Revival. Families wander by, clutching carrier bags, munching contentedly.
There are demonstrations on creating with Blue Bunny yoghurt, and the Nestle choco bake challenge. If you feel the need for a little more raw excitement, then you can climb into the 16-storey-high Skyscraper, which whisks its riders round in a huge circle at 60mph, exerting a G-force that makes you regret that last corn dog.
Behind all this jollity are bleak facts. Farm prices are plunging as fast as the Skyscraper on its downward orbit and show no signs of turning up.
The state fair highlights the link between farming and food. It is a link that, for many people, is dying: fewer and fewer of the young people in the Future Farmers of America contest are going into the family business.
In the swine barn is a board where the latest news from the Chicago futures exchanges is set out. It represents disaster for many of those who are wandering around and munching pop corn. For some, it will make more sense to burn the crop and plough it under than to harvest it.
Maybe for today, it doesn't matter, though; and there is time for just one more piece of funnel cake before the drive back home through the swaying green fields.