The results of a study by Mark Honeyman and Michael Duffy of Iowa State University on changes to the pork industry in Iowa can be found here
at the site of the Iowa Pork Producers Association. They note that although Iowa has led the nation in pork production for over 120 years, there have been profound changes to the industry in the last couple of decades. While the total number of pigs in the state remained about the same (15.5 million head in 2002!), the number of pig farms decreased by 83 percent between 1978 and 2002. The average size of pig farms increased dramatically, from about 250 pigs per farm to more than 1500 pigs. The location of pigs in the state shifted with this increasing concentration, something plainly visible in the maps to the right. In addition, the nature of the business changed, with more that half of Iowa pigs in 2002 being fed under a contract arrangement with swine companies or swine packers rather than in the traditional farrow-to-finish production of family farms.
Honeyman and Duffy conclude that pigs are now viewed differently in Iowa. Animals that once were called "mortgage lifters" in Iowa's communities are now viewed negatively, with a 2004 poll ranking hog confinement operations below prisons, landfills, and sewage treatment plants as desirable rural development. As they note, the Des Moines Zoo has added sows ready to farrow to their displays, demonstrating how "as the state becomes more removed from pig production, some Iowans now go to a zoo to see pigs."