The sign is iconic and now the last one is gone, apparently stolen. The San Diego Union-Tribune reports that last known ‘immigrant crossing’ sign disappeared from its spot alongside Interstate 5 sometime last September.

The “immigrant crossing” signs have become obsolete, said Cathryne Bruce-Johnson, a spokeswoman for Caltrans. The transportation department stopped replacing the signs years ago because it constructed fences along medians to deter people from running across highways.

The last sign, which stood on the side of Interstate 5 near the San Ysidro border crossing, vanished in September.

“It’s gone,” Bruce-Johnson said. “Caltrans crews did not remove it, so it’s assumed stolen.”

Last summer the LA Times did a story reporting that just one of the signs remained along the Interstate. The signs were originally designed because a rush of illegal immigrants in the mid to late 1980s meant people were being run down and killed crossing the interstate:

So many immigrants crossing illegally into the United States through California were killed by cars and trucks along the 5 Freeway that John Hood was given an assignment.

In the early 1990s, the Caltrans worker was tasked with creating a road sign to alert drivers to the possible danger…

Ten signs once dotted the shoulders of the 5 Freeway, just north of the Mexican border. They became iconic markers of the perils of the immigrant journey north…

In 1986, the San Diego sector recorded its highest number of border crossing apprehensions in a year: 628,000, according to Department of Homeland Security statistics. The area — geographically the smallest for Border Patrol — was once the busiest sector for illegal immigration in the U.S., accounting for more than 40% of nationwide apprehensions in the early ’90s.

In fiscal year 2016, Border Patrol agents apprehended 31,891 people in the San Diego sector suspected of crossing the U.S.-Mexico border illegally.

An article published in 2005 described the signs as a “Rorschach test” with both sides of the immigration debate seeing different things in the image of a family fleeing across the freeway. Pro-immigrant groups tend to see the signs as a symbol of the fraught nature of a broken immigration system in which people are willing to risk their lives for a chance at something better.

Joshua Wilson of the National Border Patrol Council tells the Union-Tribune, “What it symbolizes to me is how out of control things were before we put in the infrastructure with Operation Gatekeeper.” Operation Gatekeeper was a mid-90s program which doubled funding for border security. The result was a decline in the number of illegal crossings in the San Diego area with more illegal crossings happening to the east of the city.

Opponents of Operation Gatekeeper have complained that while it may have decreased the number of people killed running across California’s freeways, it also meant that more immigrants died in remote locations. In 2009, activists claimed up to 5,600 people had died crossing the border since the program began:

They estimate that as many as 5,600 people have died while crossing the border through rugged mountain and desert areas of California, Arizona, New Mexico and Texas since the operation was launched Oct. 1, 1994.

“If there was any other policy that the federal government adopted that systematically killed more than 500 people every year … those policies would be changed quickly,” said filmmaker John Carlos Frey, whose documentary “The 800 Mile Wall” is being released in conjunction with the anniversary.

But the disappearance of the last sign from that earlier era, when border crossing was much more common around San Diego, seems timely as Congress prepares to debate a deal which would finally offer protection for “Dreamers” but also fund the construction of a wall designed to make border crossing much harder.