How did the popularity of art graffiti grow in the 70 and 80s?

How did the popularity of art graffiti grow in the 70 and 80s?
After the New York Times ran an article on Taki183's tags, graffiti became a well-known art movement. Since then graffiti has grown much more elaborate than Taki's tags. Major artists like Lee Quinones, Jean-Michal Basquiat, and Lady Pink added to the movement by being featured in fine art galleries. Today graffiti is still going strong with the movement including fine art, apparel and graphic design by Cope2, Phetus, Kaws, and many others.