Various labor unions that represent public workers are sponsoring a rally today at Jefferson Square Park.The “Block Party” is part of a national day of solidarity for public workers and coincides with the anniversary of Dr. Martin Luther King Junior’s assassination. He was gunned down in 1968 in Memphis, where he had gone to support striking sanitation workers.Organizers say they also want to raise awareness of the plight of public workers in states such as Wisconsin, Ohio and Indiana, where legislation placing limits on their collective bargaining power has been passed or is under consideration. Today’s rally in Louisville begins at 5:30pm.