Come see the giant pumpkin, prize sheep, and more at state fair

It's in the dog days of August that they appear. That time of year when the season takes the nation toward crisper air and busier days of autumn, but when one's spirit still hankers for the last honeyed drops of summer. Then do the county and state fairs sprout like weeds from Maine to Montana - when those who raise prizewinning Herefords and snap beans come together with those who prefer to whirl on Ferris wheels and down corn dogs amid the crowds on the midway.

Such are the rhythms of the American summer.

So much so that this summer is punctuated by more than 2,500 fairs sprinkled across the country like commas separating one season from the next. The biggest, they say, is in Ohio, which boasts some 3 million visitors every year. The longest may be in Texas, a whopping 24-day event that apparently does justice to the big Dallas spirit. One of the oldest - a 144-year-old local agricultural fete - is tucked away in Berkshire County of Massachusetts. Overall, says the International Association of Fairs and Expositions, fair attendance in the United States is on the rise - more than 158 million visitors every year.

But here at the Minnesota State Fair, which runs through Labor Day, the fair's spirit is unencumbered by statistics. Except for a celebratory nod in the direction of ''One hundred years in the same spot,'' it continues pretty much as it always has - as a salute to the state's agricultural roots. ''Of all the big fairs in urban areas, Minnesota's is the one that has retained its emphasis on agriculture,'' says Jerry Hammer, fair spokesman. ''Most others have become ... dates for carnivals.''

Those are not idle words. A jaunt down Commonwealth Avenue - the fairground is literally a small village constructed by unemployed bricklayers during the 1930s depression - provides nary a glimpse of the carny side of the fair. Like errant children, the Tilt-a-Whirls, bumper cars, and freak shows have been tucked away on the far side of the grandstand.

What one sees instead are painted curbs, flower beds bursting with butter-yellow irises, the red and white Farmers Union booth, and the Hamline United Methodist Church hall where a kind-looking man exhorts the crowd to partake of the church supper of ''baked chicken and our special ham loaf'' now being served. It's an avenue where the lesser pursuits of the ''World's Largest Merry-Go-Round'' and the ''World's Best French Fries'' sit cheek by jowl with the Democratic Party's exhibit - ''Have your Picture Taken with Walter Mondale'' - and the AFL-CIO recruitment booth. Where the strains of ''Twistin' the Night Away'' blend with the warbled voice of the Crossroads Chapel soloist.

The crowd that floods in by the thousands in blue jeans and farmers' caps, T-shirts and running shorts, is largely a home-state one, although visitors from as far away as China and Australia have been noted. But most fairgoers hail from counties such as Crow Wing, Ottertail, and Chippewa and towns such as Pipestone, Haypoint, and Thief River Falls. Nearly all spring from solid Midwestern stock; they are a group that appreciate their own agricultural heritage.

Over in the Agricultural and Horticultural Hall, smelling sweetly of apples, county exhibits testify to this fact. ''The Story of Timber!'' and ''Wheat,'' ''Maple syrup,'' and ''Cheese,'' the banners announce. A sign in the Anoka County booth discloses that 46,800 Minnesota jobs are directly traceable to the state's lumber industry.

Here, too, one can sip a cup of local cider pressed from native Beacon apples and amble through the vegetable wing where blue-ribbon carrots stand pertly in pint boxes, their green tassels clipped like horses' manes for the show. Or gaze at the first-place white potatoes, which lie in their carton perfect and round as a dozen eggs. This year's largest pumpkin, ''Big Max,'' sits proudly on a green felt-covered table in the center of the room, oblivious to fine print adorning its belly: ''Botanically a squash.'' ''I thought so,'' sniffed one passerby.

These are fairgoers familar with nature's best. People trot their children - clad in sturdy miniature overalls and baseball caps that say ''Win Twins'' - to the famous Machinery Hill. There, giant tractors and combines gleam in the afternoon light like metal dinosaurs, looming over toddlers and farmers alike while the salesmen from John Deere, International Harvester, and Allis-Chalmers push back their colored caps and squint at tires tall enough to sit in.

At the Minnesota fair, people wander through the Creative Activities building to observe not only quilting, weaving, and woodcarving demonstrations, but also prizewinning taxidermy and decoy carving. They visit the Arts Center, the oldest building at the fair, where a realist painting, ''American Farmhouse,'' is listed as among the top five ''People's Choices.'' These are fairgoers who line up two deep around a booth whose bunting proclaims, ''All the Milk You Can Drink 25.'' And mothers who push strollers up to the freshly squeegeed plate-glass window of the Cattle Barn to get a good view of the 2 o'clock milking demonstration.

Over in the Dairy/Animal Products building, families lick mounds of snowy ice cream and linger at exhibits about meat (''America, You're Leaning on Pork'') and solar-heated ice-fishing shacks. Nearby, an air-conditioned glass booth twirls, inside of which the Regional Dairy Princess of Jasper County is sitting for her portrait - which is being carved from a 68-pound block of sweet butter by a woman in a ski jacket. Another princess offers the crowd saltine crackers crowned with fat butter chips. What happens to the butter busts? ''Us girls get to take them home.''

But perhaps it is in the animal barns - sprawling brick buildings with limestone likenesses of farm animals poking out over doorways - where the fair really comes into its own. Here, dappled Clydesdales with names like Samson and Rocket stand patiently in their stalls, their rumps flicked by pale, wheat-colored tails. Here, T-shirts are sold that say ''There's No Business Like Sheep Business,'' and signs dangle overhead: ''More Cattle in Annex'' ''Restrooms and Sheep Barn.'' In the poultry barn, cockerels, guinea hens, and game birds scratch and screech in wire cages, while next door Columbia and Suffolk sheep lie panting in their white canvas overcoats like prize racehorses.

In the Coliseum - a vault-ceilinged building large enough for a professional baseball team to play in (though it is home to the horse shows and cattle judging) - high school boys quiet their heifers by scratching their silky bellies with chrome show sticks. In the Swine Barn - where one rowdy sow has broken free of her owners and kicks pointed heels up the aisles - the judging of Cheviot sheep is under way. The judge wearing a gleaming silver belt buckle is praising a particularly ''uniform set of lambs'' that twist and bleat under their master's hand in the green-tinted-sawdust ring.

One ring away is the crossbred-pig show. where sows and their switch-toting masters circle and dart in the ring like a dance marathon waiting for the judge's decision. It is Future Farmers of America Day, and young Dean Peterson, who wears a shirt with mother-of-pearl snaps, shoves his peach-colored sow into the No. 8 pen. The judge has described her as a ''smaller pig, tight in the joints.'' But Dean is unperturbed. ''Good enough for me,'' he murmurs, as he gives his pig a flick of his switch which is unmistakably tender.