Given the screwy turn our country has taken lately, it may seem odd to tout the Stars and Stripes. But for Philadelphia, especially on its 250th birthday, the dubious present recedes before the original, utopian vision. The exhilarating ballets on this mixed repertory also take a good-natured view. According to the Russian exile George Balanchine’s 1958 Stars and Stripes and his 1970 Gershwin suite Who Cares?, America is cheerful, kitschy, swoony, sassy, silly, and fast on its feet (if a bit slow otherwise). For Jerome Robbins’s Fancy Free, cocky young sailors on furlough in New York set the tone. A perfect blend of the realistic and cartoonish, the 1944 ballet catapulted the 25-year-old Robbins onto Broadway, and it still holds audiences in its virile, comic grip. That Philadelphia Ballet’s own director, Angel Corella was astounding in this ensemble piece, during his salad days at American Ballet Theatre, bodes well for the run. Eliot Feld’s contribution is minor, but it won’t spoil the fun. —Apollinaire Scherr