The New York subway system was one of Keith Haring’s most beloved and well-worn canvases. Between 1980 and 1985, the iconic street artist created thousands of works: He would take white chalk and draw on blank panels meant for advertisements on station walls.

“I remember noticing a panel in the Times Square station and immediately going aboveground and buying chalk,” Haring once said, per Sotheby’s. “After the first drawing, things just fell into place. I began drawing on the subways as a hobby on my way to work. I had to ride the subways often and would do a drawing while waiting for a train.”

This month, 31 of Haring’s subway drawings sold at a Sotheby’s auction for a collective $9.2 million. The artist was known for his bold, colorful works addressing political and social issues, and the imaginative chalk drawings feature subjects that range from barking dogs to flying saucers to pyramids.

“Though seemingly cartoony, Haring’s work commented on important social events that contemporary New Yorkers felt were being ignored or misrepresented by politicians and the media,” writes Artnet’s Tim Brinkhof.

According to Sotheby’s, Haring called the subway his “favorite place to draw” even after his career took off—and even though he would sometimes get arrested for his creations.

Because these graffitied works were made in public spaces, many have been destroyed or lost to time. This particular selection of 31 drawings survived thanks to one avid collector: Larry Warsh, who first spotted Haring’s work on the New York subway in the 1980s. He became an early fan and subsequently bought the street artist’s pieces from people who had removed them from the walls.

“I basically hunted them down and tried to accumulate them as a body of work,” Warsh tells the Observer’s Elisa Carollo. “It was not about commerciality. It’s about historical importance.”

Leading up to the event, Sotheby’s New York displayed the art in an immersive exhibition, which staged a recreation of the subway in the 1980s, complete with vintage advertisements and benches.

Haring’s subway art has come a long way from its humble beginnings. His works once belonged to the public; now, they have high price tags and go to the highest bidder. Sotheby’s acknowledges that Haring’s original intent for the subway series was to spread his ideas in an open and approachable way.

“Art is for everybody,” says Gil Vazquez, the executive director of the Keith Haring Foundation, in a statement from Sotheby’s. “It was the overarching idea for this five-year long project. Instead of people going to museums or galleries, he was going to do the opposite. And he was going to bring the art to them to make it accessible.”

Warsh echoes this sentiment. “It was art for everyone,” he tells the Observer. And while the high price tags may be contrary to this idea, the collector hopes the sale will get the pieces (which otherwise would have been lost to time) into museums.

“I am so happy that these works will be enjoyed across the globe and hope they will go on display once more for all to enjoy as a testament to Keith’s legacy,” Warsh tells Artnet. “It is an immense privilege to have played a part in this historic moment.”