This Hell on Wheels photo contains
fedora, felt hat, homburg, stetson, trilby, business suit, boater, leghorn, panama, panama hat, sailor, skimmer, and straw hat.
There might also be
pith hat, pith helmet, sun helmet, topee, topi, dress hat, high hat, opera hat, silk hat, stovepipe, top hat, topper, beaver, porkpie, and porkpie hat.