Mexico City is the oldest and most historical capital city in North America. It's an exciting, beautiful, and magical city, which for the past few years has been fighting against serious environmental problems. It has a population of over 22 million people and it's getting bigger all the time. It's more than three times bigger than New York City and it's the largest city in the world. Every day, thousands of people move in from the country to look for work, but there aren't enough jobs for all of them, and the result is extremely high unemployment and over-population.
The city is situated at a height of 2,255 metres above sea level and is surrounded by snow-capped volcanoes. For the Aztecs, who first built the city, it was a beautiful, sunny capital, but today Mexico City is almost always covered by an enormous brown cloud of smog which is caused by the pollution coming from hundreds of factories around the city and from over three million cars waiting in endless traffic jams. Just breathing the air is the same as smoking 40 cigarettes a day! One day in the 1980s, the level of pollution in the air in one part of the city was so high that thousands of birds fell from the sky and died.
Since then, the Mexican government and private organizations have worked very hard to clean the air and control the levels of pollution, and the situation is improving. But the problem of over-population is more difficult to solve - by the year 2010, over 30 million people will live in Mexico City.