When he was assassinated, King was on the front lines with public employees organizing labor unions. His "I Have a Dream" speech was delivered at the 1963 "March on Washington for Jobs and Freedom" -- an event that explicitly linked civil rights with economic justice.
King always saw that link in the struggle of public employee unions for dignity, fair pay, fair benefits and recognition.
In April of 1968, King made his last trip, at age 39, to march with and campaign on behalf of members of the American Federation of State, County and Municipal Employees union in Memphis, Tennessee.