Mostly public sector (around 1/3 unionized). Private is around 6%[1]. And after the public sector it's transport, utilities, telecoms, construction, manufacturing. Basically a laundry list of underperformance in the US -- important sectors (govt especially) choked to death by rent-seeking and complacency.

1: https://www.thebalancecareers.com/best-union-jobs-in-america...