composed primarily of low-income households are 25% less likely to have a chain supermarket store but contain 1.3 times as many convenient stores when compared to ZIP codes composed of middle-income households. ZIP codes composed of predominantly African-American households have about half the amount of chain supermarkets, as do ZIP codes composed of predominantly White households. An assessment of 685 urban and rural census tracts spanning three states show that low-income neighborhoods have approximately half as many supermarkets and four times as many small grocery stores when compared to high-income neighborhoods. The same study also found that predominantly White neighborhoods have four times as many supermarkets as predominantly African-American neighborhoods. Also, a study of 10,763 residences in four states reported the existence of supermarkets in the surveyed residential area was directly related with a 24% lower prevalence of obesity and a 9% lower prevalence of overweight residents. Locally focused studies Studies done at the local level demonstrate similar trends to those done at the national level. There are 2.3 times as many supermarkets per household in low-poverty areas in Los Angeles compared to high-poverty areas. Predominantly white regions have 1.7 times as many supermarkets as Hispanic regions, and 3.2 times as many as African-American regions. West Louisville, Kentucky, a low-income African-American community that suffers from high rates of diabetes, has one supermarket for every 25,000 residents; in comparison, the U.S. in total has an average of one supermarket for every 12,500 residents. In Washington, DC, the city's lowest income wards (Wards 7 and 8) have one supermarket for every 70,000 people, while two of the three highest-income wards (Wards 2 and 3) have one for every 11,881 people. One in five of the city's food stamp recipients lives in a neighborhood without a grocery store. Twenty-one studies have found that food stores in low-income communities are less likely to stock healthy or fresh food or snacks, and are instead more likely to offer lower quality items at higher prices, compared to food stores in predominantly white communities. School nutrition legislation The Child Nutrition and WIC Reauthorization Act of 2004 created the team nutrition network to promote healthy eating and physical activity in school-aged children, awarding grants to states that created healthy eating and physical activity programs for the children they serve. The CDC released its own guidelines for schools to promote physical and health education for schoolchildren, specifically suggesting that