Created by editor Julius Schwartz in collaboration with writer Gardner Fox the Justice League of America (JLA) first appeared in The Brave and the Bold #28, published by DC Comics in 1960. The JLA was created as a {Silver Age} revival of the Justice Society of America {JSA}, a successful teaming of many of the major super-heroes of the Golden Age of comics. The first artist on the project was penciller Mike Sekowsky.
The original membership of the team included:
After two more appearances in The Brave and the Bold (in #29 and #30), the JLA was granted their own title, Justice League Of America. With the fourth issue of the series they received their first new member in Green Arrow. Ten issues after this the Atom joined the team as well. With issue #21 the JLA first met the JSA, creating what would become an annual tradition of meetings between the two groups.
The team's ranks have changed constantly throughout the years, with the original series ending with issue #261 in 1987. While in actuality no hero has been a member of every incarnation of the team, continuity was changed following the Crisis on Infinite Earths to make the Martian Manhunter a member of each team.
The current incarnation of the team first appeared in Justice League: A Midsummer's Nightmare, a three issue mini-series published in 1996. This led into the current series, simply titled JLA in January 1997.
Sources:
www.comics.org
Robert M. Overstreet, The Overstreet Comic Book Price Guide, 31st Edition. New York: Crown Publishing Group, 2001.