In 2004 the U.S.-Mexico border saw an average of 660,000 passenger crossings each day. Heavy trade between the two countries, as well as tourist attractions on both sides, have made it the most crossed international border in the world.
A 1,969-mile-long border divides Mexico from the U.S. The border starts in the west from San Diego, California, and runs across Arizona, New Mexico and Texas to the Gulf of Mexico.
For 1,250 miles, the scenic Rio Grande River forms the boundary between the U.S. and Mexico. Each year many tourists take float and canoe trips through the river's many canyons.
U.S. and Canadian visitors must present passports when entering and leaving Mexico. Visitors who reside in border towns and remain in Mexico for less than 72 hours are exempt from this rule.
Crossing by Car
U.S. citizens driving into Mexico must first obtain Mexican auto insurance through their carrier or rental car agency, as most U.S. policies are not valid in Mexico.
Crossing by Foot
U.S. citizens sometimes park their vehicles on the U.S. side of the border and cross into Mexico by foot for shopping or day trips. Pedestrians must always cross through official points of entry.
Crossing by Boat
In addition to complying with numerous other regulations, foreign citizens crossing into Mexico by boat must present the vessel's title or lease agreement and obtain a temporary vehicle import permit from Mexican customs officials.