A version of this story appears in the September 2020 issue of National Geographic magazine. Philadelphia detected its first case of a deadly, fast-spreading strain of influenza on September 17, 1918.

From artificial intelligence-driven efficiency to transmission bottlenecks, power industry insiders share their perspectives ...

When you receive your credit card bill, you'll notice two different balances: the statement balance and the current balance. Conventional wisdom says that you should always pay off your statement ...