U.S. Customs and Border Protection has space to hold about 300 people at the crossing, said Pete Flores, director of the agency's San Diego field office.
Trump and other officials have described the caravans and asylum seekers as evidence that security at the border with Mexico is a serious problem.
Hundreds of Central American migrants from a caravan through Mexico reunited in Tijuana on Wednesday and planned to cross into the United States together this weekend, in defiance of threats by President Donald Trump to repel them. At its peak, more than 1,000 people were walking north through Mexico. They are expected to start trying to enter the USA on Sunday. "A thief doesn't announce when he's coming, when he's going to break into your house".
'Thanks to God we're here, ' said 34-year-old Aide Hernandez from Guatemala who had four children in tow.
Jean Guerrero of NPR member station KPBS, reporting from Tijuana, says more than 200 people have arrived in the border town. They joined another group of 150 people that had arrived over the course of the previous week.
Migrants began arriving by bus on Tuesday at a shelter that was a five minute-walk from the border and within sight of a US flag fluttering under an overpass linking the two countries.
It's not clear how quickly U.S. Border Agents will be able to process the asylum applications once the migrants cross the border.
"I'm so scared", said Daisy Guardado, 40, who fled Honduras with her three daughters after a gang attacked one and killed her brother.
"I didn't come here to cross illegally". That includes Mexico, she said.
Central Americans fleeing violence have found it hard to receive asylum based on gang violence waiting for them at home, as NPR's Eyder Peralta reported in 2016. The U.S. and Mexico started coordinating flows of migrants with the unofficial ticketing system during a Haitian influx a couple of years ago, to deal with strained Customs and Border Protection resources.
Recently, asylum seekers wait only a few hours, never overnight, Flores said.
Ginger Jacobs, a San Diego immigration attorney who helped Haitians seeking entry to the U.S.in 2016, said Trump's concerns about a rush of Central Americans seeking asylum were "completely overblown".
DHS spokesperson Katie Waldman told The Hill that the department would enforce current laws and that the department does not have a policy of separating families. Critics of the caravan contend that most migrants are driven not by a need for asylum but a desire to find better jobs and lives in the United States.
Some 2,300 miles across the United States in Washington, D.C., Mexican Foreign Minister Luis Videgaray met with Homeland Security chief Nielsen to discuss Central American migration, the Mexican ministry said in a statement. "If you enter our country illegally, you have broken the law and will be referred for prosecution", Nielsen said.
That is not what the caravan participants say they plan to do.
Human rights group Amnesty International said the US and Mexican authorities must "stop demonizing participants of the caravan from Central America and respect their fundamental right to seek asylum".
A bus carrying Central American asylum seekers heads to Tijuana on April 24.
The U.S. offers asylum to those with a "well-founded fear of persecution" in their home country, on the basis of their race, religion, nationality, political opinion or membership in a certain social group.
Organizer Leonard Olsen of the Pueblos Sin Fronteras group says many migrants in Mexicali were exhausted from their lengthy journey from southern Mexico and nervous about the possibility of being detained. Despite the attention the caravan has attracted, its numbers pale in comparison to tens of thousands of mostly Central Americans came across in 2014, culminating in a standoff with protesters in Murrieta.
TT in breach of global refugee law
She said that on a weekly basis, between 150 to 200 Venezuelans come here by sea, some of them, illegally. The entire exercise was recorded by the Trinidad and Tobago Air Guard.