The 1926 heavyweight match pitting champion Jack Dempsey against challenger Gene Tunney was billed as "the greatest battle since the Silurian Age," and millions of Americans were determined not to miss it. A record-breaking crowd of 130,000 jammed the Philadelphia stadium where the fight was held, while some 39 million radio listeners nationwide gathered at city centers, storefronts, drugstores, athletic clubs, and theaters to hear live coverage...