The Washington Post has created an interactive map visualizing which chains own the most grocery stores, shown in various colors, in different parts of the United States using data on store locations from a geographic database called OpenStreetMap. The darker the shade of a color, the more stores that chain owns in a given area. According to the visualization, smaller chains like Stater Bros. Markets in California and Publix in Florida dominate coastal states, while Kroger and Walmart are dominant in the middle of the country.