What to know about the twin US-Mexico border cities Ambos, Nogales

Arizona is home to a pair of vibrant twin border cities known as Ambos, Nogales. The cities are split by the U.S.-Mexico border but share a storied history.

Here's what you need to know about the communities.

Nogales, Arizona, is about 70 miles south of Tucson and 180 miles south of Phoenix. The cross-border community straddles the international boundary between the U.S. and Mexico with its sister city, Heroica Nogales, Sonora, immediately on the other side. 

The twin cities are often referred to as Ambos, Nogales, meaning “both Nogales.” The name “Nogales” comes from the Spanish word for walnut, referring to the now-extinct black walnut trees that once dotted the surrounding hills of the cities. 

How long have the cities been separated by a barrier? 

The first fence that divided the twin cities was put up by the Sonora governor in 1915 as a result of the Mexican Revolution. The 11-foot wire fence was torn down four months later. 

In 1918, the mayor of Nogales, Sonora, ordered that a 6-foot fence, consisting of six wires, be erected along the international boundary between his city and Nogales, Arizona. The mayor wanted the fence in order to better control the cross-border flow of customs agents and soldiers. 

During the 1910s, the Mexican Revolution and World War I caused stricter U.S. border control measures. In August 1918, the U.S. and Mexico went to war during the “Battle of Ambos Nogales,” which led to the creation of permanent border fences meant to control the movement of people.

U.S. authorities subsequently installed a 2-mile fence topped with barbed wire along the border. 

How many pedestrians cross the border there every year?

Nearly 2.9 million pedestrians crossed through Nogales ports of entry to shop, eat, study and work in fiscal year 2023, per U.S. Customs and Border Protection data. The number increased by roughly 1 million since the pandemic hit in 2020. 

Similarly, there were nearly 3.8 million passenger vehicles that crossed through the border city in 2023. 

Are the cities similar in population? 

Nogales, Arizona, has a population of nearly 20,000 people, while Nogales, Sonora, boasts a population of 264,782. 

The population of Nogales, Sonora, increased by more than 20% from 2010 to 2020. Maquiladora factories have incited tremendous growth in the Mexican city as residents from central and southern Mexico move there to seek employment. 

Meanwhile, Nogales, Arizona, has seen many of its residents move out of the city to seek opportunities elsewhere in the state. Many businesses along the historic Morley Avenue have shuttered as the city continues to rely on international commerce. 

Have a news tip or story idea about the border and its communities? Contact the reporter at josecastaneda@arizonarepublic.com or connect with him on X, formerly known as Twitter, @joseicastaneda.