JACKSON (AP) — A group of congressional leaders has announced planning is under way for next year’s event commemorating the 50th anniversary of the Freedom Rides that challenged segregated interstate travel in the South.

Democratic U.S. Reps. Bennie Thompson of Mississippi, James Clyburn of South Carolina, John Lewis of Georgia and Bob Filner of California held a news conference earlier this week in Washington, D.C.

Thompson said Thursday that after the May 2011 event in Jackson, has ended, a memorial will be left in the city honoring the civil rights activists who participated in the Freedom Rides.

Lewis and Filner were among the 1961 Freedom Riders. Organizers said the protest ended segregation in southern bus and train stations and airports.