I was born near Waterloo, Iowa. (By coincidence, I now work in Waterloo, Ontario.) It takes no great brain to know that John Wayne, originally Marion Morrison, was born in Winterset. Winterset is in Madison County, and is where by coincidence the movie "The Bridges of Madison County" was filmed, some scenes being fillmed a few paces from his birthplace. (During filming, Clint Eastwood and I shopped at the same Taerget store, but that is just another coincidence.)
Johnny Carson was born in Corning, Iowa. Herbert Hoover was born in West Branch. Mamie Eisenhower, wife of the 34th president) was born in Boone (her home now sits on the land where by coincidence my grandmother used to live). Elijah Wood and Terry Ferrell came from Cedar Rapids. Wyatt Earp came from Pella. Harry Reasoner was from Dakota City (near where my grandparents lived, by coincidence). Brandon Routh (who by coincidence went to the same university I did, at the same time) is from Norwalk. Donna Reed was born in Denison. James Van Allen was born in Mount Pleasant (and was my Astronomy professor by coinci ... aw, to heck with it). Bill Daily and Cloris Leachman attended Roosevelt High School in Des Moines. Dear Abby and Ann Landers were from Iowa, so was Folger's Coffee's Mrs. Olsen, so was Norman Borlaug, and so was guy who wrote "The Music Man."
Let's not forget that some dude named Ronald Reagan (though born in Illinois) got his major broadcasting start in Iowa. Some other dude named Burt Lancaster filmed his final movie there, near Dyersville. Cary Grant died in Iowa, hours before he was scheduled to go on stage in Davenport (for "An Evening with Cary Grant").
Movies shot partly in Iowa include "Bridges of Madison County," "Field of Dreams," "FIST," "Take This Job and Shove It," "Cold Turkey," "Puppetmasters," "Miles From Home" and "The Straight Story."
As for Waterloo, what notables were from Waterloo? Well, for starters, the Sullivan Brothers! ANYONE from Waterloo would know THAT! (There is a major edifice in the city in their honor.) Olympic Wrestling Gold Medalist and esteemed coach Dan Gable went to Waterloo's West High School. President Herbert Hoover's wife, Lou, was from Waterloo.
A bit o' advice, to any presidential candidate of any party: if you're going to come and pander to Iowans, for goodness's sake, do your damn homework.