The advisory is the third this year requested by U.S. Ambassador to Mexico Tony Garza. In a statement, Garza said more than 100 violent deaths along the border since June and the killings of 18 Nuevo Laredo policemen convinced him the warning was still necessary.
"These disturbing reports make clear that Mexico needs to do much more to bring safety and security to our common border," he said.
The last advisory was issued in April and expires Friday.
Mexico's government responded that it "maintains a constant fight against organized crime and has made a series of efforts to abate violence on the border."
The past two advisories have angered Mexico, which relies heavily on U.S. tourism and bridles at criticism from its powerful northern neighbor.
Growing violence and a battle between Mexico's two main drug gangs have caused a spike in violence along the border, especially in Nuevo Laredo, across from Laredo, Texas.