The bowler hat, or derby, was designed in 1849 by London hat-makers Thomas and William Bowler. It gained unexpected popularity on the American frontier due to its sturdy, rounded crown and snug fit, which resisted being blown off in strong plains winds. Historical photographs show famous figures like the Sundance Kid, Bat Masterson, and members of the Wild Bunch wearing bowlers, not the wide-brimmed styles later immortalized by film. John B. Stetson's 'Boss of the Plains' hat, introduced in 1865

Bowler Hats: A Stylish Throwback to the 1960s | Amazing Time Capsule