FACTBOX: Some facts about U.S.-Mexico ties

(Reuters) - U.S. President-elect Barack Obama meets Mexican President Felipe Calderon in Washington on Monday to discuss immigration, security, trade and the economy.

Here are some facts about the issues likely to be discussed:

THE DRUG WAR

* Mexican cartels smuggle some $40 billion worth of illegal drugs every year into the United States, the world's biggest market for narcotics. The drug gangs arm themselves with huge arsenals of smuggled U.S. weapons.

* Some 5,700 people were killed last year by drug cartels in turf battles with rival gangs and fights with the Mexican military, sent in by Calderon to try to stop the violence. U.S. officials worry the killing could spill over the border into the United States.

* The United States has so far released almost $300 million in anti-drug aid for Mexico under the so-called Merida Initiative, a three-year, $1.4 billion package for Mexico and Central America pledged by President George W. Bush during a visit to Merida, Mexico, in March 2007.

IMMIGRATION

* An estimated 12 million undocumented workers and their children live in the United States, slightly more than half of them Mexican.

* Obama won two-thirds of the Hispanic vote in the presidential election and many hope he will pass reforms to give more immigrants legal status.