Kenneth Stone, Professor of Economics at Iowa State University, in a paper published in Farm Foundation in 1997, found that some small towns can lose almost half of their retail trade within ten years of a Walmart store opening. He compared the changes to previous competitors small town shops have faced in the past—from the development of the railroads and the Sears Roebuck catalog to shopping malls. He concludes that small towns are more affected by "discount mass merchandiser stores" than larger towns and that shop owners who adapt to the ever-changing retail market can "co-exist and even thrive in this type of environment."[126]