Left: Former President Herbert Hoover, on stand at right, addresses the delegates of the Republican National Convention in Convention Hall in Philadelphia in this June 22, 1948 photo. The press section is at the lower right. Philadelphia has hosted eight presidential conventions, but none since that steamy summer a half-century ago, when not one, but three came to town in the span of a month. (AP Photo, File)

Right: Democratic presidential candidate former Vice President Joe Biden and his wife Jill Biden wave at supporters on a video screen during the fourth day of the Democratic National Convention, Thursday, Aug. 20, 2020, at the Chase Center in Wilmington, Del. (AP Photo/Andrew Harnik)