The U.S. pork industry continues to concentrate by location and size of producer.

According to Glenn Grimes and Ron Plain, University of Missouri agricultural economists, from 1999 to 2004, nine states that produced 0.5 percent or more of the U.S. pig crop increased their market share from 61.3 percent in 1999 to 67.2 percent in 2004.

The growth states are Iowa, Kansas, Minnesota, Michigan, North Carolina, Oklahoma, Pennsylvania, Utah and Virginia.

Conversely, 13 states with 0.5 percent or more of the U.S. production lost market share from 35.4 percent in 1999 to 30.1. These states include Arkansas, Colorado, Georgia, Illinois, Indiana, Kentucky, Missouri, Nebraska, Ohio, South Dakota, Texas and Wisconsin. These states market share declined from 35.4 percent of U.S. production in 1999 to 30.1 percent in 2004.

The economists predict more concentration in the industry, but say the amount if very unpredictable.