SEATTLE, WA - Seattle's annual May Day observation happens Tuesday afternoon with parades and protests planned - and officials are warning workers, visitors, and others with business in the downtown area to prepare for serious traffic disruptions.

May Day will kick off Tuesday afternoon with the 19th Annual May Day March for Immigrant and Workers Rights. That event begins at 2:30 p.m. at Judkins Park in the Central District. Attendees will march from the park to 2nd Avenue and Spring Street in downtown Seattle. Seattle police will shut down streets as the march moves through downtown.

King County Metro is predicting "major transit delays," and has already rerouted some buses.

A right-wing group, Washington State Patriot Response, will rally at Westlake Park beginning around 3 p.m. That group, which includes members of Patriot Prayer and the Proud Boys, is coming to Seattle to counter-protest left-wing activists. "The left has been able to run amok in this country completely unchecked since the 1960s in regards to social issues, education, anti military, the welfare state and so much more. It needs to stop. It is time for Conservatives get off the couch and start taking action," Washington State Patriot Response wrote on its Facebook page.

But Washington State Patriot Response might be making a tactical error. The Seattle Industrial Workers of the World has called for "decentralized" action on Tuesday. "We believe that this year's May Day events should be throughout the city at different times and different locations and hosted by various groups in order to prevent direct repression by the Seattle police and to make disruptions of our events by outside agitators more difficult," the group wrote of this year's May Day.

May Day sometimes involves vandalism and confrontations between police and activists. May Day 2017 in Seattle was largely peaceful, however, with only five arrests and no property damage. The right wing Patriot Prayer group made its first appearance in Seattle that year. The group's leader, Joey Gibson of Vancouver, is running for U.S. Senate against Maria Cantwell.

Famously, the conservative and left-wing protesters at last year's gathering at Westlake came together to smoke a "peace joint."