Immigration relations between the U.S. and Mexico is often portrayed as single-lane highway into the U.S., but the reality is that Mexico is constantly dealing with an influx of American retirees, the Washington Post reported.

In fact, the Mexican government created a special visa just for those individuals who offer the country an economic boost.

The Residente Temporal visa is especially provided to individuals who do not work in Mexico but are economically self-sufficient. This includes the about 1 million American citizens who have crossed the border to retire in a warmer climate that offers great food and a lower cost of living.

The visa is for what the country considers "temporary residents" who stay for longer than 180 days but less than four years, according to the Mexican government's website.

The new type of visa went into effect in 2012, when the government revamped its visa system and restricted tourist visas to 180 days.

But that hasn't changed the issues that Mexicans face with American visitors.

The Washington Post reported that–whether out of ignorance or hoping to fly under the radar–visitors from the U.S. either do not get any documentation, or they overstay the legally allowed period.

Though there is an estimated 1 million Americans living in Mexico, no one really knows how many American citizens–including illegal immigrants–are currently residing in Mexico.

A reform prior to 2012, in 2008, erased a harsh punishment for those unable to produce proper documentation.

At the time, the offense was punishable with up to 10 years in prison. But since then, and overall, punishment against illegal immigrants is lax, the Washington Post reported.

Mexico does firmly remind U.S. citizens heading to major retirement areas to get their visas, but if they do not, they are essentially given amnesty.

The government pursues those without legal documentation by simply requiring them to pay a fine and get the documentation, as long as they have not committed a crime, and the non-document offenders are not faced with deportation.