US Vice President Kamala Harris on Tuesday met Mexican leader Andres Manuel Lopez Obrador to discuss ways to lower a record increase in migration from Central America by attacking poverty
Ms Harris told Mr Lopez Obrador that relations between the two countries were entering a "new era".
They witnessed the signing of an agreement about the work the two countries' development agencies will do in Central America, then met for talks on the "root causes" of migration.
"I strongly believe that we are embarking on a new era that makes clear the interdependence and interconnection between nations," Ms Harris said at the start of the meeting.
Mexican Foreign Minister Marcelo Ebrard wrote on Twitter after the meeting that the discussion had been "very successful".
The two leaders addressed the economy, security co-operation and development in southern Mexico and Central America, Mr Ebrard said.
Mr Lopez Obrador, who built a working relationship with Donald Trump despite the former US president's economic threats and insults against Mexico over migration, said his government was very interested in maintaining good relations with Washington.
The administration of President Joe Biden has been struggling with the number of migrant children and families arriving at the US-Mexico border, mainly from Central America.
Since Mr Biden took office in January, the number of migrants taken into custody each month at the border has risen to the highest in 20 years.
The White House regards Mexico as an important partner in decreasing the number of migrants and development in Central America, where relations between national governments and Washington are increasingly fraught.
The US and Mexico largely agree that they need to attack the underlying causes of poverty and violence to stem migration from the "Northern Triangle" of El Salvador, Guatemala and Honduras.
It was not immediately clear if Ms Harris used the meeting to push Mexico for more effort in detaining migrants.
Her spokeswoman and senior adviser, Symone Sanders, said on Monday that the two sides would discuss increasing enforcement.
But Mr Ebrard said they would not.
"We are not going to talk about operations or other things," he said earlier on Tuesday.
"What is going to be the focus of attention today is how we can promote development in the short term in these three countries."
Temporary work visas would be on the agenda, Mr Ebrard said.
Mexico detained 91,000 illegal migrants, a fifth of them minors, in the first five months of the year, immigration authorities said on Monday.
Some members of the Biden administration think Mexico could do more.
Ms Harris, asked by Mr Biden to help stabilise Central America, has promised an extra $310 million in aid to soothe the impact of the pandemic and last year's hurricanes in the region.
Mexico has launched programmes paying for planting trees and youth unemployment benefits for Salvadorans and Hondurans on a limited scale, and plans to add Guatemala, Mr Ebrard said before the meeting.
On Monday, Ms Harris met with Guatemalan President Alejandro Giammattei and said the two leaders had "robust" talks on fighting corruption to deter migration from Central America.
"Do not come" to the US, she told potential migrants, which immigration advocates said went against the spirit of the administration's commitment to a more humane approach.