When Does "DC: The New Frontier" #6 (2004) Take Place?

"DC: The New Frontier" #6 "Justice League of America" is a superhero comic-book written by Darwyn Cooke and released September 29th, 2004. 

It takes place on an alternate timeline of the fictional DC Comics Universe in the year: 

1958 AD 

We know this because, although (like the previous issue) there are no time setting free-floating text bullets, Lois Lane is reporting early in the book and uses "several hours ago" while referring to events from the final pages of the previous issue, "DC: The New Frontier" #5 (2004), which takes place in 1958 AD. 

Furthermore, a third through the comic, King Faraday says, "for the last few weeks" when referring to a status that began in #4, which also takes place in 1958 AD. 

Additionally, there is a two-part epilogue that is unplaceable. HOWEVER, the first part heavily uses text from the Democratic Presidential Nomination Acceptance speech given by John F. Kennedy on July 15th 1960 AD. Also, the second part is clearly referencing the story from the comic-book "The Brave and the Bold" #28 v1 (1959), which released December 29th, 1959 AD with a "February-March 1960" cover date. Based on this, this epilogue MIGHT take place in 1960 AD. 

This comic-book was retroactively collected into a "DC: The New Frontier" volume 2 paperback as well as a complete hardcover. 

It is a chronologically midway comic in the DC Comics Universe multiverse timeline (a chronological first comic to feature the Justice League characters). It can be read after the previous issue, "DC: The New Frontier" #5 (2004). 

It was adapted to animation as part of "Justice League: The New Frontier" (2008).