"What good does it do to be able to eat at a lunch…

American minister and civil rights activist Martin Luther King Jr. (1929-1968), referencing the restaurant sit-ins for civil rights, was reported calling for economic justice in a United Press International (UPI) story at a strike in Atlanta, Georgia, on December 20, 1964:

“Dr. King, who returned here last week after accepting the Nobel Peace Prize in Norway, asked, ‘What good does it do a man to have integrated lunch counters if he can’t buy a hamburger?’”

A UPI story published on July 7, 1965, from Petersburg, Virginia, mentioned the “hamburger” saying again:

“‘What does it profit a man to go to an integrated lunch counter without enough money to buy a hamburger?’ he asked.”

Martin Luther King Jr. used the “hamburger” saying a third time, in an economic protest in Washington, DC, as reported in the New York (NY) Times on August 5, 1965:

“What good does it do to be able to eat at a lunch counter if you can’t buy a hamburger?”

The Voting Rights Act of 1965 was signed into law the next day, on August 6th. King would use the “hamburger” saying right before his death, in Memphis, Tennessee, during a garbage workers strike. The Associated Press reported on March 19, 1968:

“‘But what does it profit a man to be able to eat at an integrated lunch counter if he can’t afford a hamburger and a cup of coffee?’ he asked.”

Wikipedia: Martin Luther King Jr.
Martin Luther King Jr. (born Michael King Jr., January 15, 1929 – April 4, 1968) was an American Baptist minister and activist who was a leader in the Civil Rights Movement. He is best known for his role in the advancement of civil rights using nonviolent civil disobedience based on his Christian beliefs.

21 December 1964, New York (NY) Times, “King Threatens Boycott To Aid Scripto Strikers,” pg. 33, col. 1:
ATLANTA, Dec. 20 (UPI)—The Rev. Dr. Martin Luther King Jr. said today the “civil rights movement and the labor movement must stick together,” and threatened a national boycott to aid workers striking against an Atlanta concern.

Dr. King, who returned here last week after accepting the Nobel Peace Prize in Norway, asked, “What good does it do a man to have integrated lunch counters if he can’t buy a hamburger?”

3 July 1965, Los Angeles (CA) Times, “Dr. King Calls Vietnam Negotiation Essential,” pt. 5, pg. 4, cols. 1-2:
PETERSBURG, Va. (UPI)—Dr. Martin Luther King Jr. said Friday night the United States must negotiate a settlement in Vietnam and announced he was considering joining in peace rallies and teach-ins.
(...)
King said the employment section of the civil rights bill would not totally solve the problem. He said civil rights organizations would have to make sure the law was implemented.

“We must get rid of economic injustice,” he said.

“What does it profit a man to go to an integrated lunch counter without enough money to buy a hamburger?” he asked.

5 August 1965, New York (NY) Times, pg. 12, col. 5:
Economic Freedom for Negroes Stressed by Dr. King in Capital
Crowds Hear Leader Proclaim New Cry of Civil Rights Movement, While Urging Home Rule in Washington
Special to The New York Times.
WASHINGTON, Aug. 4—Ignoring Nazi pickets and bomb threats, the Rev. Dr. Martin Luther King Jr. moved into Washington’s ghettoes today and told crowds of his admirers that economic freedom was the new cry of the civil rights movement.

Speaking at street corner rallies, to an assembly of ministers and in a Virginia suburb, the Southern civil rights leader stressed that “economic freedom” was one of the immediate goals of the Negro revolution.

“What good does it do to be able to eat at a lunch counter if you can’t buy a hamburger?” he asked. “What good is it to live in integrated housing if you can’t afford to take your family on a vacation? Why be able to stay in hotels and restaurants if you don’t have the money to take your wife out to dinner?”

19 March 1968, Cumberland (MD) Evening Times, “Civil Rights Leader Backs Refuse Issue,” pg. 2, col. 3:
MEMPHIS, Tenn. (AP)—Dr. Martin Luther King told striking garbage workers and their supporters Monday night that “genuine equality means economic equality.”
(...)
He told the alternatively shouting, applauding audience—a number of white people sprinkled throughout—that civil rights had mainly been won.

“But what does it profit a man to be able to eat at an integrated lunch counter if he can’t afford a hamburger and a cup of coffee?” he asked.

Twitter
Feeding Texas‏
@FeedingTexas
“What good is having the right to sit at a lunch counter if you can’t afford to buy a hamburger?”—Martin Luther King, Jr. #hunger #MLK
8:18 AM - 17 Jan 2011

Daily Kos
Martin Luther King, Jr.: ‘Our struggle is for genuine equality, which means economic equality’
By Laura Clawson
Monday Jan 21, 2013 · 2:21 PM EST
(...)
As Meteor Blades describes, for King, the fight for civil rights didn’t end with black people being allowed to eat at lunch counters without being attacked. It didn’t end with the right to vote (not that voting is by any means an uncontested right today). Time and time again, he made clear that civil rights and labor rights were tightly linked, saying, for instance, to strikers in Memphis, Tennessee, in March 1968:

Now our struggle is for genuine equality, which means economic equality. For we know now, that it isn’t enough to integrate lunch counters. What does it profit a man to be able to eat at an integrated lunch counter if he doesn’t have enough money to buy a hamburger? What does it profit a man to be able to eat at the swankest integrated restaurant when he doesn’t even earn enough money to take his wife out to dine? What does it profit one to have access to the hotels of our cities, and the hotels of our highways, when we don’t earn enough money to take our family on a vacation? What does it profit one to be able to attend an integrated school, when he doesn’t earn enough money to buy his children school clothes?

ThinkProgress
Aviva Shen
New Orleans-based journalist, focusing on criminal justice.
Jan 20, 2014
4 Ways Martin Luther King Was More Radical Than You Thought
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2. He was a critic of capitalism and materialism. King was a strident critic of capitalism and materialistic society, and urged Americans to “move toward a democratic socialism.” Referring to the now iconic Greensboro Lunch Counter sit-ins, he asked, “What good is having the right to sit at a lunch counter if you can’t afford to buy a hamburger?”

Twitter
Occupy Wall Street‏
@OccupyWallStNYC
“What good is having the right to sit at a lunch counter if you can’t afford to buy a hamburger?” - Martin Luther King Jr
9:52 PM - 16 Aug 2015

Common Dreams
Published on Thursday, February 11, 2016 by Common Dreams
Reality Check for Democrats: Would Martin Luther King Be Supporting Bernie?
byJeff Cohen
(...)
1965: After passage of the landmark Civil Rights Act of 1964 and the Voting Rights Act in 1965, King became even more vocal about economic rights: “What good is having the right to sit at a lunch counter if you can’t afford to buy a hamburger?”

Twitter
Felesia Bowen‏
@felesiabowen
“What good is it to sit at the lunch counter if you can’t buy a hamburger” Dr. Martin Luther King Jr. #SDOH @PublicHealth @TuskegeeUniv
9:10 PM - 15 Nov 2016 from Jackson, NJ