What has happened to the urban population of mexico city since 1950?

That article noted that the core municipality of Mexico City in 1950 had 2.23 million residents out of the urban area's fewer than 3 million and comprised only 54 square miles (139 square kilometers). ... By 2000, the former city had a population of only 1.69 million, a 40 percent loss from 1970

written by alan ward and published in 2003. ward is a historian and was a professor at the university of connecticut.

if this isn't what you are looking i would like to know more details.