What you need to know:
Festivities kick off with a rock concert at Westlake Park from 10 a.m. to 5 p.m., with bands including Smashie Smashie and istabcapitalists.
A historically peaceful march for workers and immigration rights begins about 2:30 p.m. in the Central District and heads through Capitol Hill, then toward downtown.
The annual anti-capitalist demonstration is set to begin at 6 p.m. at Westlake Park in the heart of downtown.