Justice League of America #29

Justice League of America number 29 was published by DC Comics in August 1964. The issue was written by Gardner Fox and illustrated by the artist Mike Sekowsky, who served as the primary visual architect for the Justice League during the Silver Age of comic books. This period was characterized by high-concept science fiction narratives and an expansion of the DC multiverse, with this specific issue featuring the first crossover between the Justice League of America and the Justice Society of America, marking a significant milestone in DC's editorial strategy to connect their Golden and Silver Age iterations.

The design of this issue relied on the quintessential mid-century superhero aesthetic, utilizing vibrant, primary-color palettes and dynamic, action-oriented layouts typical of the era. The cover art, famously depicting a split composition of both hero teams, was designed to emphasize the scope and scale of the collaborative event. Upon its release, the issue was well-received by readers as it formalized the concept of parallel Earths, specifically Earth-One and Earth-Two, a narrative device that would underpin much of the publisher's storytelling for the following two decades.