Boy, it took me a while to make sense of the theme today. I'm not sure why, really, because it seems so obvious now. Different flags. Not always physical flags, as in the cases of "Black Flag" (band or insecticide?) and "Red Flag." All the rest are flags I can picture. Not bad at all. All symmetrical, and a nice revealer.
I thought this was a very nice grid, but Frannie comments that there was a lot of straight-up trivia - the kind of thing that you either know or you don't. Like 28A: *Creator of Sheriff Deadeye and Cauliflower McPugg (REDSKELTON), 31A: Sabin's study (POLIO), 48A: First song on "More of the Monkeys" (SHE) (who knows this?), and four stacked on top of each other in the NE - 17A: Alma mater for Toni Morrison and Zora Neale Hurston (HOWARD), 7A: Where Whole Foods is headquartered (AUSTIN), 15A: Fast-food chain founded by Italian immigrants (SBARRO), and 18A: *1971 song with the lyric "Helter skelter in a summer swelter" (AMERICANPIE). Sure, that last one is a gimme for anyone within ten years of my age, and the others are guessable with a cross or two, but it just seems like a lot.
That being true, there was a lot I loved in here. EMETIC (58A: Emergency room agent), AGGRIEVE (18A: Distress), TIRADE (60A: Vehement venting), and IRRITANT (17D: Pebble in one's shoe, e.g.) are all nice words. WHENCE... ASPECT... it's filed with 'em.
My favorite clues were the schoolyard-related pair of 10D: Hide seekers (TRAPPERS) and 2D: Made it? (TAGGED). I just love that last one.
Not much to bark at. I like the crossing of SHE and HER, and many clues were entertaining.
A very nice Thursday.