Seven-year-old Mimi Meade winces from the sting as Dr. Richard Mulvaney inoculates her April 26, 1954 in McClean, Va., with the new Salk polio vaccine. Mrs. John Lucas, a registered nurse, holds Mimi's arm steady as she gets one of the first injections of the countrywide test. (Photo by Harvey Georges/AP Photo)

Pan Am aircraft – here in 1963 with the abbreviation PAA for Pan Am Airways – could be seen everywhere, including from the freeway in New York before the Strato Clipper took off for Europe in 1963. (Photo by Imago)

Soldiers and firefighters carry the body of Chilean President Salvador Allende, wrapped in a Bolivian poncho, out of La Moneda presidential palace after it was bombed during a coup by Gen. Augusto Pinochet in Santiago, Chile, September 11, 1973. (Phoot by El Mercurio/AP Photo)

A female motorcycle cop directs traffic wearing crash helmet, Haywarket Square, Boston, Massachusetts, 1979. (Photo by Spencer Grant/Getty Images)

Members of the Hitler Youth who are trained to report airstrikes repaining their bicycles. Published by: “Die Sirene”. 1942. (Photo by Herbert Hoffmann/Ullstein Bild via Getty Images)

Chinese models with animal-themed body paintings pose during a campaign for animal protection at Sanya Color Zoo in Sanya city, south China's Hainan province, 10 January 2016. The girls wearing strapless bras and short pants only were colored with animal-themed paintings such as zebra, cheetah, tiger and peacock. They paraded throughout the newly-opened Sanya Color Zoo and met visitors to take pictures, causing envies from netizens living in north China who are suffering chills. (Photo by Imaginechina/Splash News)

Contestant Nathalie De Oliveira of Brazil prepares backstage before the final show of the Miss International Queen 2016 transgender/transsexual beauty pageant in Pattaya, Thailand, March 10, 2017. Thai contestant Jiratchaya Sirimongkolnawin was crowned Miss International Queen 2016. The 2016 show was postponed from November last year due to Thailand's mourning period of its late King Bhumibol Adulyadej who died at age 88 on October 13, 2016. (Photo by Athit Perawongmetha/Reuters)

A participant holds his dog as colored powder is thrown into the air during the Color Run in Lausanne, Switzerland, 12 September 2015. The international 5km running event is inspired by the Hindu Holi spring festival of colors. (Photo by Valentin Flauraud/EPA)