They don't. The real problem is that most cities in Mexico don't follow a comprehensive urban management policy, including water treatment facilities, garbage disposal, increased traffic, etc. As a result, many cities have overstretched resources, resulting in increased pollution. For example, Mexico City (capital of the country) grew more than 5% every year from 1970 to 1980, resulting in one of the cities most afflicted by air pollutin in the world during the 1990's.
Traffic and pollution
The cities that have the worst air pollution is Pittsburgh and Los Angeles
cities
25a. Air pollution normally increases along with population growth. This increasing pollution is a big problem for many cities. 25b. Air pollution normally increases along with population growth. This is a big problem for many cities. Which is a vague pronoun?
santafe
Demographic explosion
First I should mention that Mexico and Canada are countries not cities, and Mexico has a larger population. Mexico has a population of 107,431,230, and Canada has a population of 33,739,900.
Some positive aspects to growing cities would be community and improvement to the economy. Some negative aspects would be pollution and crime rate.
With a population 110,201,789 in 2009
No. Mexico has more than 3,000 cities, towns and villages. Mexico City alone has a population of 21.16 million people; more than 5 times the whole population of Puerto Rico.
because it has a fast growing population
ducky fanpatrick recrdo