Not much; at least not on the border gateways. Considering the US-Mexico border is one of the most active in the world, security agents tend to "take a sample" out of the hundreds of thousands that cross the border on a daily basis.
In most cases, they will take a quick look inside your vehicle and check at your body language; if you seem nervous or uncomfortable they may ask you to open up your belongings to look for forbidden items - especially weapons and ammo, which are illegal in Mexico.
None of them will ask for ID, passport or any other identification document, because they know the US border security is much more stringent in this regard -- they don't care if you come to Mexico, because they know you will bring dollars to the economy; but YOU should care to have a proper ID if you want to get back to the US.
Border security.
The US Border Patrol, part of Homeland Security.
Unlike the U.S.-Mexico border, which is a no man's land full of security fences, barbed wire, drones and infrared cameras, the Guatemala-Mexico border is almost imperceptible -- there are no fences among both nations; only a clearing between both countries. The Guatemala-Mexico Border has a length of 871 Kilometers (542 miles) and is defined at some stretches by the Usumacinta, Salinas and Suchiate Rivers.
To the US-Mexico border? Northern Mexico is close to the border.
Montana does not border Mexico.
The states that border Mexico are California, Arizona, New Mexico and Texas...
Yes, Mexico does border the U.S
None. Mexico's border touches New Mexico's state limit (and US border).They share a common border.
US-Mexico border ("Frontera Mexico-Estados Unidos").
Which state has a longer border with Mexico, Texas or New Mexic?
None. Mexican deserts are located in northern Mexico, close to the US-Mexico border. These include the Sonoran desert to the northwest, along the Mexico-Arizona border, and the Chihuahuan desert, to the northeast from the New Mexico-Mexico Border to the Mexico-Texas border.
The border between Mexico and the United States is the Rio Grande River.