The advisory follows the kidnapping of four Americans earlier this month in the city of Matamoros. The state's Department of Public Safety said "cartel activity" made trips to Mexico a "serious risk."
Their companions are recovering in a U.S. hospital. So far, only one arrest has been made in relation to the kidnapping.
Before the pandemic halted travel, some 1.2 million American citizens visited Mexico for health care. The number is rising quickly again, with border restrictions eased.
The State Department said the victims, who were found alive after days in captivity, are back on U.S. soil. Officials said they are in the process of returning the remains of two others to the U.S.
The abduction took place on the streets of Matamoros, Mexico. The FBI is offering a $50,000 reward for the return of the Americans and the arrests of those involved.
Tens of thousands of people filled Mexico City's vast main plaza Sunday to protest President Andrés Manuel López Obrador's electoral law changes they say threaten democracy.
As fentanyl deaths soar, political pressure is growing to stop Mexican cartels that smuggle the drug. Experts on drug trafficking say trying to lock down the Mexican border is an impossible goal.
His comments are important, because democracy in Latin America is in retreat. The president of El Salvador has announced he will defy constitutional term limits and run again for president next year.
The two leaders set out to talk about working together on migration, fentanyl interdiction and the economy. But first, they sparred over the history of U.S. support in Latin America.
The White House is expanding a pandemic-era program allowing the administration to quickly expel people from Nicaragua, Cuba and Haiti who illegally cross into the country from Mexico.
The riot occurred at the notorious Cereso state prison in Juárez. The mayor, Cruz Pérez Cuéllar, told local media that armed gunmen had entered the prison.
The U.S. government sued Arizona Gov. Doug Ducey and the state Wednesday over the placement of shipping containers as a barrier on the border with Mexico, saying it is trespassing on federal lands.
It's the latest development in a homicide case that continues to capture attention both in the U.S. and abroad.
Hundreds of thousands of people marched in Mexico's capital Sunday to support President Andrés Manuel López Obrador and his proposals to reform the country's electoral authority.
Día de los Muertos is a Mexican holiday that commemorates loved ones who have died. It is believed their spirits return to their families, who put up ofrendas, or altars, on Nov. 1.