posted mostly because i thought it was funny, the ML USA orgs map is propably big too but not as much i think
also im surprised how castroism is a big influence on some trot orgs, its probably the ones that are anti-embargo are also castro influenced 
If you actually read the chart, most of the splits re-merged. With the remaining parties being DSA, SA, and CPUSA (the original party). Most of the splits that do remain have become committees within one of the bigger parties.
With some of the older trot splinters just focusing on things like art and newspapers.
I also think that SA and DSA are federated and I know CPUSA does a lot of work with both depending on the size of the local. I see all the groups at rallies around me and they all know each other and are friendly.
Ah, forgot PSL, they're also pretty closely integrated with groups like CPUSA and DSA when it comes to actual action.