Mexico City is built on the Ancient Aztec city of Tenochtitilan. Built from the 14th to 16th centuries A. D., it was constructed atop the water of a 650 square mile area that was made up of 5 great lakes, featuring 10 large ports. It began as a small island and grew above the water through a system of chinampas or floating gardens. The soil on these chinampas was among the most productive in the world. People traveled by canoes filling the city's lake canals. Planted along the edges of the floating islands were these trees called ahuejotes (a type of cypress), which were useful in compacting the soil and regulating the sun and the wind.
In 1519, the Aztec Empire covered an area of 625,000 square miles and had 150,000 inhabitants. (At this time London had 200,000 thousand people and Madrid had 64,000 people.)
Even though Tenochtitlan was a lake dwelling, water based society, which sustained the livlihood of its inhabitants, the Spanish did not have the same respect for the water and had it drained. They saw it as an obstacle for their horses and heavy canoes. Beginning in the 16th century, the lake city was transformed into one dry land.
In the 20th century the city began to experience explosive growth. At the beginning of the 20th century the population of Mexico City was only a little bit larger than it was in 1519. This did not last long, however, with growth going from 250,000 people in a 29 square mile area to 3.2 million people in a 150 square mile area in 1953. Because of this rapid growth, the city needed to increase its water supply. In order to do this, they drilled wells which caused the subsoil to sink. in 1948 rates of sinkage up to 18 inches per year were recorded in the Mexico City Historic Center. In the 1960's, the Metropolitan Zone grew by as much as 8% a year and by 1970 Mexico City had 9 million inhabitants living in a 400 mile square area. In 1996, it had 17 million people living in an 870 square mile area and its getting larger everyday.
Population growth rates in the Mexico City Metropolitan Zone had dimished significantly over the past 10 years, standing now at about 2% a year. The population of the Districto Federal or the D.F. is growing at a rate of .5% a year. However, even with these relatively low numbers there is still concern over immigration to the city from the countryside. It's estimated that about 150 new people reach the D.F. everyday. IF you combine this with the birthrate expected over the years this raises the population to approximately 30 million by the year 2020.
Throughout its history, Mexico City has received a massive inflow of population from the other parts of the country as well as the rest of the world. Key Mexican states which have contributed significant population sectors to the capital include Michoacan, Puebla, Jalisco, Guerrero, Nuevo Leon, Hidaldo, and Guanajuato. Mexico City also holds approximately 900,000 Indios (Indians) from more that 10 indigenous cultures. Between 1980 and 1990, 20 % of the people immigrating to Mexico City came from other countries, especially Argentina, Brazil, Colombia, China, Cuba, Spain, France, Italy, and Japan. (other pics)