Part I. Poverty is on the run -- Part II. Enrichment didn't come for the reasons you imagine -- Part III. It came because ideas, ethics, rhetoric, and ideology changed -- Part IV. The causes of the causes were not racial or ancient.

Prior research shows grocery stores reduce prices to compete with Walmart Supercenters. This study finds evidence that the competitive effects of two other big box retailers - Costco and Walmart-owned Sam's Club - are quite different. Using city-level panel grocery price data matched with a...