At the mid-century point folks were concerned about an explosive growth in the world's population.

The Popexpo site [http://www.popexpo.net/ -- no longer on-line] explored both explosion and stabilization of the world's population via exhibits and a simulation just as the 21st century approached.

Day of 6 Billion, sponsored by Population Action International, is designed for older students and covers not only the issues, but also some solutions.

Another interesting page is the "POPClock" from the U.S. Census Bureau. As soon as the site is entered, a population ticker is activated; it just keeps going and going...

Now that the 2000 census data, Census Scope, has been compiled, the results of demographic trends can be compared with 1990. The data is broken down into regional information.PBS' site relates stories from around the globe about the impact of a world population of 6 billion.

Day of 6 Billion!

http://www.unfpa.org/6billion/

POPClock - U.S. Census Bureau

http://www.census.gov/ipc/www/clock.html

Census Scope

http://www.censusscope.org/

PBS 6 Billion

http://www.pbs.org/sixbillion/