The first issue of the current run was the 500th ongoing issue of a normal Justice League comic.

We get to this number by adding up the issues in the JLA main line. The League runs through four numbering sequences:

1. The original series – Justice League of America (vol 1) #1-261 (261 issues)
2. The JLI era – Justice League #1-6, Justice League International #7-25, Justice League America #26-113, 0 (114 issues)
3. The Big Seven era – JLA #1-125, 1000000 (126 issues)
4. Current series – Justice League of America (vol 2). #0-38+. (39 issues)

Ignoring annuals, specials, mini-series, and variants that makes a total of 540 issues. An argument could be made for the inclusion of Legends and Midsummer’s Nightmare as they bridged the gaps between the first and second and the second and third incarnations, but I’m only including regular ongoing issues.

The first issue of the current run, Justice League of America (vol 2) #0, would have been the 502nd issue if there had been continuous numbering. The 500th issue would have been JLA #124. If we ignore specially numbered issues (0 and 1,000,000) the 500th issue would have been the first issue, Justice League of America (vol 2) #1, of the current run.

So technically, the most recent issue Justice League of America (vol. 2) #38 is actually issue #539 is the entire run. The next landmark issue, overall #550, will be Justice League of America (vol. 2) #49 in about a years time.

It’s a pity they didn’t renumber when they had the chance.