U.S. officials closed the Mexican border Sunday at the San Ysidro port of entry in San Diego, California, following a protest in which migrants rushed the area, reported the Los Angeles Times.
The protesters say they are part of a migrant caravan that has been making its way north from Central America to seek asylum at the U.S. border, reported the publication.
Here are five things to know about the San Ysidro port of entry.
1. It’s one of the world’s busiest border crossings
The San Ysidro port of entry between San Diego and Tijuana, Mexico, is the busiest land border crossing in the western hemisphere, according to the federal government. It’s one of three ports of entry in the San Diego area.
The checkpoint, which connects Interstate 5 on the U.S. side with Mexican Federal Highway 1, processes an average of 70,000 northbound vehicle passengers and 20,000 northbound pedestrians each day.
In 2017, the port of entry processed 27.5 million vehicles containing 47.6 million passengers, along with 16.5 million pedestrians, reported the U.S. Department of Transportation.
2. It’s being expanded
A $741 million expansion will increase the number of northbound lanes from 25 to 34, with 62 vehicle inspection booths, according to the federal government.
As part of the project, the southbound lanes are being realigned to make room for the northbound expansion. Interstate 5 southbound will be expanded from five lanes to 10.
The changes are being made to handle an 87 percent increase in traffic by 2030 predicted by the San Diego Association of Governments, according to the government.
3. It’s got a long history
The San Ysidro border crossing dates back to the 1848 Treaty of Guadalupe Hidalgo, which established the U.S.-Mexico border, according to the San Diego History Center.
The Tijuana River served as the original dividing line, but the port of entry was later moved and, especially after the Sept. 11, 2001, attacks, became more militarized, according to the center.
4. It’s heavily used by commuters
Many of those who cross the border at the San Ysidro port of entry aren’t migrants or asylum seekers, reported The Outline. They’re commuters from Mexico heading to jobs in the United States.
In all, about 6.8 million people live on the San Diego-Tijuana border, with a combined annual economic output of $220 billion, according to the publication.
5. It’s been temporarily closed
All northbound traffic lanes and pedestrian bridges were closed Sunday afternoon after protesters, who say they are part of a migrant caravan seeking asylum in the U.S., rushed the crossing, reported CNN.
About 500 migrants overwhelmed Mexican police and rushed the border, according to the network.
Videos show U.S. agents firing tear gas at the protesters, reported the BBC.