The 20th century is a period of history that a lot of people from present times are personally familiar with and often the most personally interested in. So it's no surprise that one of the two primary AH.com forums for discussing general history is specialised solely on the 20th century.
Points of divergence discussions, general AH discussion and various timelines and other AH works are posted in this discussion forum if their point of divergence is set after the year 1900 AD/CE.
The “After 1900” Forum is actually younger than even the New Board, being founded on the 4th October 2005. This is due to the fact that it and its sister forum, “Before 1900”, were originally a single forum, and were only split off into two forums by Ian in October that year. The single major discussion forum was a holdover from the days of the Old Board.
The split was necessitated by the increasing amount of 20th century AH discussions in the first year and a half of the New Board - splitting the original big forum into two smaller ones helps with sorting and finding the discussions and works more easily, to readers and writers alike.
General discussion about alternate history scenarios where the divergence from real history happens from 1900 AD onward. Post “what if” questions and talk about the results. NOT debates about present-day politics.