The graduate students at my university (a relatively large state school in the US) are considering joining a union. To help decide whether to sign a union card in support of joining the union, I'm interested in more information about how unions have helped graduate students at other universities. What are some improvements to graduate life gained by graduate students at other universities upon joining a union?

I'm primarily interested in student-body-wide benefits, instead of student-specific claims (e.g. "my advisor treated me better with the union behind me" is not what I'm looking for).