Proms, parties and gender politics: amazing photos from American dancefloors – and what they tell us about a changing nation

<p>From George Balanchine to the Rockettes, the US magazine regularly ran lavish photo spreads dedicated to dance, with the myriad ways people moved their bodies holding up a mirror to the shifting times</p><p>Life magazine launched in 1936. Its aim: to show the US the world, in pi