In fiscal 2017, agents apprehended 303,916 people, an 82 percent decrease.
The sign's image has been the source of controversy, with some seeing it as an offensive caricature of Mexican immigrants.
Justin Akers Chacon, a professor of Chicano studies at San Diego City College, said critics of the sign's imagery felt that it dehumanized migrants by likening them to animals.
Critics are also bothered by the way the sign's message fit into the immigration enforcement system.
"The deaths of migrant crossers was treated as an acceptable consequence of the enforcement model, not a reflection of the failure of the model," Akers Chacon said.
An early version of the sign was entirely text: "Caution watch for people crossing road."
Motorists weren't able to read and process that sign quickly enough, so Caltrans asked artist John Hood to design an image to convey the message.
"It doesn't just mean they are running across the freeway," Hood told the San Diego Union-Tribune in 2005, describing his choice of imagery. "It means they are running from something else as well. I think it's a struggle for a lot of things, for opportunities, for freedom."
Caltrans installed 10 signs, focusing on areas like San Ysidro and the San Clemente checkpoint where migrants were known to cross the interstate on foot frequently.
The silhouette of a man with a mustache and woman in a dress running with their young daughter, her hair in pigtails trailing behind her, has been repurposed by different sides of the immigration debate over the years.