I actually never knew that, but it certainly explains why public schools have been shoving her down kids' throats for decades.
You can read her bio on Wikipedia. She did align herself with some truly unsavory elements, from the Socialist Party (Communists, really) to the terroristic, subversive Wobblies (IWW).
https://en.wikipedia.org/wiki/Helen_Keller
I was fascinated with Helen Keller as a kid. All the children’s books (including her autobiography) only emphasized her overcoming horrendous disabilities and the genius of Anne Sullivan. I was an adult before I knew about her political activities. She was pretty much a pawn of John Macy.