A huge wall, 24 kilometers long and 12 meters high, separates Tijuana and San Diego, two border cities located in the northwest of the American continent. One belongs to Mexico and the other to the United States.

Their proximity and mutual interrelation give both cities a series of quite palpable similarities, although, of course, there are also differences that make it almost impossible to think that they are side by side.

Among the things that San Diego and Tijuana have in common is that they share almost the same weather conditions. Located in a semi-arid zone with a Mediterranean climate, most of the year there is good weather and pleasant temperatures in both places.

Their orography is another similarity, as the cities are surrounded by mountains and canyons. The vegetation and fauna is very similar, and both have the Pacific Ocean right next to them.

Given the population density in the area and the economic opportunities, there has been a great urban growth in the last years, which has resulted in diverse migratory phenomena of people looking for a better opportunity.

People from different states and nationalities can be found in these cities and that gives it a unique social richness.

Biculturalism is another aspect to highlight, since in Tijuana 1 out of every 4 people speaks English, while half of the Americans in San Diego speak Spanish. Basically 'Spanglish' has become the unofficial but quite common sublanguage.

When it comes to negative things, one always tries not to go into details, but unfortunately San Diego and Tijuana have two of the most polluted beaches that exist in the Pacific Ocean, which makes them unsuitable for swimming due to the high amount of bacteria in the sea. Much of that pollution comes from the Tijuana River.

Air quality is also not very good in Tijuana and it is common to see a gray cloud in the morning sky. This is caused by traffic (which is increasing), as well as industrial activity.

Leaving the bad behind, if you are a person born in the 80's or 90's you probably grew up watching cartoons in English, since there was no Spanish TV channel showing children's content, so many learned this language easily.

On the other hand, both cities have to worry about earthquakes due to their proximity to the San Andreas fault. Their dry scrublands also make them prone to periodic forest fires.

Going back in time, it was common that border restrictions used to be much more relaxed 4 decades ago and there was a free transit of people between the two cities, for shopping, tourism or to visit family, even without the need to carry a visa.

Today, if you want to cross into the U.S. you must do it through one of the ports of entry, either Otay or San Ysidro, the latter being the second most congested international access in the world. The long lines to go to the "other side" can last up to 5 hours if you are unlucky. From south to north, for those going to Mexico, the wait can extend up to an hour and a half, especially at 5 p.m. when everyone gets off work.

Jumping into the realm of differences, San Diego is called "America's Finest City" because it is the most expensive city to live in the United States. Tijuana, on the other hand, is called "The Gateway to Mexico", "The World's Most Visited Border City", or simply "TJ" by tourists, and it costs 4 times less to live there than in San Diego. Therefore it is not surprising that thousands of citizens work in the United States, but have their residence in Mexico, not only young people but even retirees who have acquired several properties in our country.

Tijuana and San Diego have formed the largest metropolitan area of the border, as it also includes Rosarito, Tecate, Chula Vista and National City.

Talking about the inhabitants, San Diego has more population with 3.3 million people, while Tijuana has 2.2 million.

In terms of transportation, Tijuana lags behind, lacking an efficient mass transit system. The thousands of cabs, trucks and vans generate a daily traffic congestion that is a nightmare. On the other hand, San Diego has a trolley, a light rail that can take you from downtown to the border with the city of Tijuana in only 45 minutes.

In terms of economic activities, Tijuana depends on medical tourism, the maquiladora sector and the rich gastronomy. In San Diego, commerce, defense, the military sector and tourism are prolific and sustaining.

Both cities have many attractive places to visit. Tijuana has Avenida Revolucion, Playas de Tijuana, CECUT and numerous restaurants in Zona Rio. San Diego has the advantage of being home to the San Diego Zoo and San Diego Zoo Safari Park; there is also Sea World, Seaport Village, the USS Midway, Balboa Park and the Gaslamp Quarter.

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