US Secretary of State Antony Blinken has held talks with Mexican President Andrés Manuel López Obrador, as a growing migration crisis causes chaos on their shared border.
The high-level meeting came as pressure grows on the White House to stem the influx of migrants to the US.
US officials said last week that up to 10,000 people were crossing the southern border every day.
Mr López Obrador is willing to limit people crossing Mexico towards the US.
Mexico's president gave a positive assessment of the talks in his country's capital, Mexico City, but gave little details as Mr Blinken left.
Speaking ahead of the summit he had called for more efforts to address the root causes of migration and warned that it could become a key issue in the 2024 US election.
Former president Donald Trump has taken an increasingly hard-line stance on the border and will reportedly unleash a massive crackdown on undocumented migrants if returned to office next year.
"We have to take care, because campaigners use this issue as a rallying cry," Mr López Obrador told reporters. "It is more efficient and more humane to invest in the development of the people and that is what we have always proposed."
Wednesday's meeting came after Mr López Obrador and President Joe Biden agreed in a phone call last week that urgent action was needed to address border security.
Mr López Obrador told reporters after the call that Mexico was "going to help, as we always do" to tackle the flow of migrants to the US.
In a statement earlier this week, the state department said the meeting in Mexico City, which also included Homeland Security Secretary Alejandro Mayorkas, would focus on "unprecedented irregular migration in the Western Hemisphere and identify ways" each country can address border security challenges
But it comes as record numbers of migrants cross into the US from Mexico. The number of people apprehended at the US southern border exceeded two million, both in the 2022 and the 2023 fiscal years.
US Customs and Border Protection [CBP] officials said in a statement on Friday that there were more than 190,000 apprehensions in November alone.
The figures have become a political vulnerability for Mr Biden, with the Republican-controlled House of Representatives refusing to allocate new military funding to support Ukraine without a commitment to reinforce the border.
"We are facing a serious challenge along the southwest border and CBP and our federal partners need more resources from Congress - as outlined in the supplemental budget request - to enhance border security and America's national security," Troy Miller, acting head of US Customs and Border Patrol, said on Friday.
Ahead of the meeting attention in US media turned to a migrant caravan of about 7,000 people which is making its way towards the US from southern Mexico.
The caravan left from the southern Mexican city of Tapachula, near the country's southern border with Guatemala, on Christmas Eve.
Its leaders carried a banner reading "Exodus from poverty".
So far, the caravan - reportedly made up of migrants from Honduras, El Salvador, Venezuela, Haiti and other countries - is about 1,000 miles south of the US border.