States are part of countries, and countries may be grouped by other areas, like continents, hemispheres, or a political or ...

It’s a small world. It’s a wide world. Both phrases are used in lyrics, titles and more. A more accurate statement might be: Earth’s circumference (at the equator) is 24,901 ...

We study the causes of “nutritional inequality”: why the wealthy eat more healthfully than the poor in the United States. Exploiting supermarket entry, household moves to healthier neighborhoods, and ...