I believe the US Army wore peaked caps in the 1820's (a rather ugly pancake crown with cord decoration radiating from the centre button, decorative bands to the sides and a flat peak). It was superseded by the 1833 leather folding cap.

In 1839 or so, the US Army adopted a new peaked cap, far smarter with a vertical round peak. Infantry was pale blue with a folding neck-curtain, dragoons dark blue with a yellow band and artillery dark blue with a red band. It was worn during the US-Mexican War of 1846-48 and indeed through the 1850's until superseded by the 1858 pattern fatigue cap (aka bummers' cap)