The Iowa state fair started in 1854 and is one of the most well known and largest state fairs in the United States with over a million people turning up for the 11 day festival that kicks off on the second Thursday every August (Photo: AP/Facebook)
Tom McDonald, of Ryan, Iowa, left, and his son Brad put a flag on the back of their boar Big Buck after winning the big boar contest. Competitions for the biggest ram, pigeon, bull and rabbit are also organised (Photo: AP)
The Butter Cow displayed at the Iowa State Fair in Des Moines, Iowa. Sometimes it seems like all visitors are clustered around Butter Cow. The creamy creation has been among the state fair's top attraction since 1911 (Photo: AP)
Other than the tractor pull, activities at the fair include monster arm wrestling, wood chipping, pie eating and outhouse racing (Photo: Facebook)
Attractions other than butter sculptures include a Ferris Wheel, one of the world's biggest livestock shows and the country's biggest state fair foods department (Photo: Facebook)
Max Petzenhauser, of Roland, Iowa, looks at his cell phone as he rests with his hog Chico after showing it in FFA competition (Photo: AP)
Sarah Pratt works on a butter sculpture of author Laura Ingalls Wilder with her daughter Grace, left, at the Iowa State Fair in Des Moines, Iowa. More than 1 million people typically visit the Iowa State Fair annually (Photo: AP)