King's name and legacy have often been invoked since his death as people have begun to debate where he would have stood on various modern political issues were he alive today. For example, there is some debate even within the King family as to where he would have stood on gay rights issues. Although King's widow Coretta has said publicly that she believes her husband would have supported gay rights, his daughter Bernice believes he would have been opposed to them. The King Center lists homophobia as an evil that must be opposed.

In 1980, King's boyhood home in Atlanta and several other nearby buildings were declared as the Martin Luther King, Jr. National Historic Site. At the White House Rose Garden on November 2, 1983, U.S. President Ronald Reagan signed a bill creating a federal holiday to honor King. It was observed for the first time on January 20, 1986 and is called Martin Luther King Day. It is observed on the third Monday of January each year, around the time of King's birthday. In January 17, 2000, for the first time, Martin Luther King Day was officially observed in all 50 U.S. states. This is the only Federal holiday dedicated to an individual American.

Many U.S. cities have officially renamed one of their streets to honor King. King County, Washington rededicated its name in honor of King in 1986. The city government center in Harrisburg, Pennsylvania is the only city hall in the United States to be named in honor of King.

In 1998, Alpha Phi Alpha Fraternity was authorized by the United States Congress to establish a foundation to manage fund raising and design of a Martin Luther King, Jr. National Memorial. King was a prominent member of Alpha Phi Alpha, the first intercollegiate Greek-letter fraternity established for African Americans. King will be the first African American honored with his own memorial in the National Mall area and the second non-President to be commemorated in such a way. The King Memorial will be administered by the National Park Service.

King is one of the ten 20th-century martyrs from across the world who are depicted in statues above the Great West Door of Westminster Abbey, London .

There are a few interesting stories on King in Hamilton Jordan's book, "No Such Thing As A Bad Day".

King in popular culture

    * Several popular songs have been written about or reference King, most notably “Abraham, Martin & John” (1968) by Dion DiMucci, “Happy Birthday” (1980) by Stevie Wonder (released as part of Wonder's campaign to make Martin Luther King Day a national holiday), and "Long Way To Go" By Gwen Stefani and Andre 3000 which also has extracts from his famous "I Have a Dream" speech, as well as Rage Against the Machine's "Renegades of Funk."

    * The band U2 wrote 2 songs as a tribute to King and his work, "MLK" & "Pride (In the Name of Love)". However, the song "Pride (In the Name of Love)" contains a historical error, as the first line of the last chorus (which references King's assassination) reads "Early morning, April 4/Shot rings out in the Memphis sky", whereas King was killed shortly after 6 p.m. - early evening. U2 vocalist Bono admits he "screwed up" when writing the lyrics and now performs the song live with the correction.

    * King was featured in the January 20, 2005 installment of The Boondocks comic strip, in which young Michael Caesar imagines King enjoying his birthdays celebration by engaging in a number of modern hip hop dances. A year later, King was the central figure in the January 15, 2006 episode of The Boondocks television series, "The Return of the King". The animated program depicted a fantasy world in which King was not fatally shot, but instead went into a coma, and awoke thirty-two years after his shooting to find that his ideals of non- violence are met with disdain in the post-9/11 era. The episode was a theoretical look at what King would think of modern Black America.

    * The difference in philosophy between King and the pre-hajj Malcolm X is part of the inspiration for the relationship between comic book characters Professor Charles Xavier, the leader of the X-Men and his rival Magneto.

    * Speculative fiction author Harlan Ellison, who attended the march in Montgomery, Alabama, penned his experience in a short story entitled "From Alabamy", With Hate.