I’ve read that Walmart has actually been losing some market share to Dollar General. DG has pursued a successful business model in opening locations in very small towns that are attractive alternatives to a long drive to Walmart for customers who are looking for some basic everyday items.
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Interesting, since opening in small towns is how Walmart got started.
And Dollar General is getting attacked for putting mom and pop retailers out of business just as Wal-Mart was in the 1980s and 1990s.
Where even Walmart won’t go: how Dollar General took over rural America
https://www.theguardian.com/business/2018/aug/13/dollar-general-walmart-buhler-haven-kansas
Dollar General opens stores in TINY towns. The link posted above is a good article that describes this.