A snaking line of traffic was visible at the country's busiest land border crossing Tuesday morning after Customs and Border Protection announced it would close multiple entry lanes at two San Diego-area ports of entry in anticipation of the so-called migrant caravan's arrival.
CBP shut down at least three lanes of the San Ysidro Port of Entry on Tuesday around 8 a.m. to traffic flowing the United States. At least one northbound lane was also to be closed at the Otay Mesa POE, according to the agency.
Travelers heading north from Mexico into the United States should anticipate longer wait times, CBP said.
"I work over here in San Diego and I cross over there every day," said Ricardo Fonseca, who lives in Tijuana. "It was packed full of people. They couldn't tell who was crossing who, you know?"
The closures were said to be "in preparation for the migrant caravan and the potential safety and security risk that it could cause," CBP said in a statement released Monday.
CBP said it does not expect lanes to reopen before the caravan arrives at the border.
Foot traffic in the area was also impacted, pedestrians told NBC 7 Tuesday.
"Today there's a lot of people crossing in San Ysidro," said Paulette Macias who live in Mexico and works in San Diego. "I changed my commute and went a different way because there is a long line. Otherwise, it will take hours to cross."
While thousands of Central American migrants were still at least 1,300 miles from Tijuana, a smaller group of about 350 people arrived there on Tuesday and a much smaller group of nearly 80 people had arrived on Sunday after splitting from the caravan.
The Associated Press reported that an additional 1,000 or so migrants were in shelters in Mexico City on Tuesday.
Members of all groups planned to seek asylum within the U.S.
In October, President Donald Trump threatened to close the southern border to address the caravan if the situation worsened, and CBP acknowledged Friday that option is still on the table.
CBP said they would install "port-hardening" infrastructure equipment during the lane closures as part of preparations for their arrival.
"These preparations include training exercises, deploying additional CBP personnel, and partnering with the U.S. military to harden our ports of entry and the border area between those legal crossings into the U.S.," Pete Flores, Director of Field Operations for CBP in San Diego, said in a statement.
Video captured at the border shows U.S. Marines installing razor wire and barriers.
More than 1,00 Marines were deployed to the border last Thursday to begin their work with Operation Secure Line in support of the U.S. Customs and Border Protection.
The Department of Defense insisted last week that the troops were sent there to help CBP and nothing else.
CBP said their specific duties include installing barbed wire to make walls less scaleable, and reinforcing construction areas so that people could not cross into them.
Officials said the military’s involvement in the operation will be temporary. The end date for assisting at the border is Dec. 15.
The San Ysidro POE processes an average 70,000 vehicle passengers and 20,000 pedestrians into the United States each day. An expansion project is currently underway to accommodate an expected 87 percent increase in vehicle traffic by 2030, according to the U.S. General Services Administration.