Board Thread:General Discussion/@comment-26838855-20190803131136/@comment-4021389-20190804123649

Construction timeline for the Empire State Building:

https://keithyorkcity.wordpress.com/2013/02/20/the-empire-state-building-constructing-the-worlds-tallest-building-in-just-17-months/

Construction seems to be completed until the last 30 floors or so, with the framing reaching the spire, so it might be around late October-early November 1930.