With so little public display time, Indecline’s work often gets wider exposure via the news media. The group also photographs and videotapes its work to distribute on social media.

“These things aren’t meant to really stay up very long,” said the artists’ spokesman. “Much of this is built for the day of instantaneous posting and social media, so it lives indefinitely on the internet.”

Heather E. Dunn, a professor at the Institute for Doctoral Studies in the Visual Arts in Portland, Maine, said Indecline represents a hybrid of artist and activist known as “artivists.”

“It’s a way to engage the masses that maybe wouldn’t go to a museum,” Ms. Dunn, an expert in street art, said. “It’s a way to bring art to them. It’s a way to bring a political message to them. In a lot of ways, I find that street art is more powerful than just about any other art that’s being made at the moment.”

Ms. Dunn said that even though illegal art created on other people’s property had long existed, street art with a more political focus gained momentum in the United States in the 1980s, when new laws in places like New York changed graffiti from a misdemeanor to a more serious crime. The art became a de facto antigovernment act.

Now, with heightened security and surveillance, the decision by some artists to be anonymous is an additional act of resistance. “It’s really hard to remain anonymous in the culture that we have right now,” Ms. Dunn said. She noted other street artists doing similar political work, like Denis Ouch in New York and Plastic Jesus in Los Angeles.