What Is Happening to Martin Luther King, Jr.?

So how did King go from being unpopular, to, many years after his death, very popular? 

Two years before King was killed, a Gallup poll had found that almost two-thirds of Americans had an unfavorable opinion of Dr. King and just one third had a positive opinion.

We believe two things happened. 1. Americans began to change their mind about King, but also 2. Americans began to invent a version of King that was more acceptable, more respectable. In order to honor King, he needed to better suit their own tastes, their own politics.