I had the same question as labratory. Even though Outta Leftfield says he couldn't possibly tell us he immediately does so IMO.
1945-72 Prior to this was pre integration. So it was after baseball was integrated. Though one might argue it did not fully come in until majority of teams were integrated. But now I am probably nitpicking, something you all will likely agree I do too much of. Ends with the beginning of the expansion era.
So here is my theory. Prior to the golden era baseball was diluted because blacks not allowed. The golden era ended when expansion began and it was once again diluted.
Based on this logic I would argue we are once again entering a new golden era. It has been decades now since the last expansion team was added. And we have more players entering the game from South and Latin countries, plus from across the Pacific, indeed from all over the world that the game is certainly no longer diluted. With all the drug testing including blood testing and aggressive investigating MLB is serious about pushing PEDs out of the game so stats are no longer inflated. Attendance and revenues are at an all time high. So I am declaring the beginning of a new golden era of baseball.
All that is left to decide is when we should call the expansion era to have transitioned to the steroids era and what year to designate as the end of the steroid era.
My personal vote for the year of transition from steroid era to new golden era would be last year. That was the year baseball added blood testing for HGH and forced the suspensions of multiple players in the absence of positive tests. Evidence from investigations alone for the most part were used with the 2 most notable being Braun who had escaped a year before on a technicality and Arod who got nailed for an entire season. While PEDs will probably always be around to some extent as long as the game is played by humans there is little doubt in my mind vast majority are now clean or realizing it may be too difficult to confidently cheat the game to continue if they have been using.
All that will leave is deciding what year the expansion era ended.