Welcome to Mexico City! Mexico City is one of the largest populated cities. It’s built on a lake called Texcoco that is constantly sinking; it has sunk more than 9 meters in some areas in the last 100 years. Mexico City sits on a basin called the Valley of Mexico. Mountains surround the Valley and have a mild climate with rich soil. The first settlers that arrived in the Mexico Valley were the Aztecs about a thousand years ago. The Aztecs created a mighty empire with the Tenochtitlan people but in 1521, Spain took over. The Tenochtitlan people were destroyed. Some 300 years later, in 1821, Mexico won its independence back from Spain. Life was tough for some Mexican Farmers. About 15% of the land was suitable for farming. Most of the land was too dry, rocky, or mountainous to grow crops. At one time, farmers were the backbone for the Mexican society, but now many farmers have to sell their land in order to survive. Sometimes, they go to work for wealthy plantations for more money. Usually, wages are low resulting to poverty and unemployment in rural Mexico. Many farmers move to the city in hopes of finding jobs that will give them decent pay and give their families a brighter future. During the 1970’s and 80’s, about 1,000 people a day have moved to the Capital. Now, many try to cross the U.S boarders. Urbanization creates problems in Mexico City. There are too many people not enough land. Mexico City is expanding, and suburbs are spreading into the mountains. Rapid growth has had a negative impact on Mexico City’s environment. The air pollution is the worst. In 1991, the air quality was a public risk for 355 days. Thick blankets of smog hang over the city. Many residents suffer from asthma or other diseases. At the time pollution was thought to cause 1,000 deaths and 35,000 hospitalizations per year.