The 7 main worldwide regions are the 7 continents, including North America, South America, Eurasia, Africa, Australia, Oceania, and Antarctica. Eurasia is a combination of Europe and Asia, with Eastern Europe and Western Asia acting as a subtle border between the two. Only North and South America are in the Western Hemisphere and are separated by the Isthmus of Panama; the remaining continents are in the Eastern Hemisphere. Antarctica is unique since it is the only continent to have no permanent human civilizations. Africa, a continent with great geographic diversity, has its regions separated mostly by the Saharan Desert. We then reviewed the major time zones in the US: Eastern (Pennsylvania and other east coast states), Central (Illinois, Wisconsin, and more), Mountain (Arizona, Montana, and more), Pacific (California and other west coast states). Alaska and Hawaii-Aleutian standard time is also used. Important figures in the history of time zones include Sir Sandford Fleming, who first proposed time zones, and Benjamin Franklin, who first proposed daylight saving time.