The right hat can make all the difference in a patriotic costume. Imagine Uncle Sam without his hat - it's just a guy in red and white pinstripes. Or what would Yankee Doodle be without his hat? Where would he stick his feather and call it Macaroni? Hats and wigs have been status symbols for centuries - including the time of the Founding Fathers. Adding a patriotic hat to your costume could very well take you from lower class citizen to general of the Continental Army.
Abraham Lincoln's top hat that he wore to Ford's Theatre on the night of his assassination is one of the Smithsonian Institution's most prized possessions. Nothing says "Abraham Lincoln" more than a stovepipe hat. For revolutionaries, however, a tricorn hat is crucial to distinguish you from the crowd. It may not be as practical as it once was, but for fashion's sake? It's a must for any late-18th century costume. Even General George Washington wore one to fend off the British. Don't forget your musket to go along with it.
Maybe your interest in patriotic hats stems from another great American war - the Civil War. Union soldier hats and Confederate soldier hats are easily identifiable and with the right accessories can make your Civil War soldier costume come to life.