Women first started shaving their legs during WW2 because of a Nylon shortage.

When Nylons were first introduced to the USA around 1939, they blew up. Up to 4 million pairs of stockings were bought each day. Women (and men) loved that “second skin” that could make even the hairiest, driest legs look like they were hand blown by angels.

In 1945, Du Pont shifted its manufacturing from wartime materials to nylon stockings, and launched a promotional campaign in the same year. This was not a good mix; it got people way too excited, and sparked riots all across the country!

In Pittsburgh, 40,000 women queued up for 13,000 pairs of stockings, for example. When they realized that the supply could not match each of their demands, street fights broke out. It took Du Pont several months to ramp up production to meet demand. In the meantime, women faced a nylon stocking shortage, and had to resort to shaving their legs.

(Source)