Has Wal-Mart Killed the Small Business Sector in the U.S.? We looked at the evidence. 

Sobel, Russell S. and Andrea M. Dean. "Has Wal-Mart Buried Mom and Pop?: The Impact of Wal-Mart on Self Employment and Small Establishments in the United States." Economic Inquiry 46, No. 4 (October 2008), pp. 676-695.

Abstract: Saving traditional small ‘mom and pop’ businesses has been a justification for political and court decisions preventing Wal-Mart from opening new stores virtually everywhere across the United States.  We present the first rigorous econometric investigation of how Wal-Mart actually impacts the small business sector.  We examine the rate of self-employment and the number of small-employer establishments using both time-series and cross-sectional data.  Contrary to popular belief, our results suggest that the process of creative destruction unleashed by Wal-Mart has had no statistically significant long-run impact on the overall size and profitability of the small business sector in the United States.

UPDATE (Dec. 08) - Click here to read our response to the Anti-Wal-Mart group's critique of our article.

This paper also formed the basis for the article:

Dean, Andrea M. and Russell S. Sobel, “Has Wal-Mart Buried Mom and Pop?” Regulation Magazine (Spring 2008), pp. 2-10.

And the article was featured in the following radio and television interviews:
7/3/08 US News & World Report interview and article by Matthew Bandyk
8/5/08 KION 1460 AM in Salinas, CA interviewed by Mark Carbonaro
8/11/08 West Virginia Public Broadcasting (statewide) interviewed by Emily Corio
8/15/08 State Journal Article by Pam Kasey (page 19)
8/15/08 Article in the Bluegrass Beacon by Jim Waters
8/18/08 Hoppy Kercheval statewide talkshow (WV Metro News Radio)
8/18/08 Fox Business Network (National TV) interviewed by Stewart Varney

9/18/08 Wall Street Journal
9/20/08 The Rural Blog