Uncle Sam has a lot of celebrity fans! Jennifer Hudson (in Roberto Cavalli) celebrated the Fourth of July with an outdoor performance at the Boston Hatch Shell, Jennifer Garner and Ben Affleck brought their patriotically-outfitted daughter Seraphina to a bash in Los Angeles, and Katharine McPhee (in a jumpsuit by The Hellers and a Theonne blazer) performed the national anthem at Bryant Park in New York City. "It's one of my favorite holidays," McPhee told InStyle.com. "I've just always kind of been patriotic." And she's not the only one—see who else cheered the red, white, and blue in the gallery.