It's anyone's guess why we had to have them - they were phenomenally ugly - but the late 1960-s-1970's fashion statement for both men and women was bell-bottomed pants. They began (with a gentle flare) in the realm of jeans then fanned out wider and into polyester in the disco years. Two small dogs or cats could have lived happily under the "elephant bells" of the mid 1970's.
Bell bottoms were originally part of the traditional sailor's uniform. The wide leg made it easier to remove their boots in an emergency. By 1813 they are described as having been worn on American vessels, and by the mid-1800's were regulation in the Royal Navy. The pants entered the mainstream through the counterculture movement of the 60's, and were seen as early as 1964 in the T.A.M.I. show.
Baby boomers wore lthem with love beads, peace symbols and tie-dye shirts. There is a certain irony here: an antiwar movement dressed in military apparel originally purchased at surplus stores. In areas where the pants weren't available, college students began modifying regular jeans, sewing in fabric to widen the area from knee to cuff.
Never inclined to miss market share, the fashion industry jumped on board. By the 1970's bell bottoms were being manufactured in polyester and corduroy as well as the ever-popular denim.
Top 25 "It" products of all time: #10 -- Bell bottomed pants