The number of people working in the World Trade Center (WTC) on an average work day prior to and including September 11, 2001 was approximately 50,000. According to U.S. Government Department of Labor investigators, the normal peak working population of the twin towers on any given day was about 50,000. Of course the majority of these people were public and private office workers. Plus some clients, vendors, and guests could also be included since they did visit retail stores, private businesses, and government offices.

Prior to 9/11/2001 the World Trade Center with its two rectangular marvels of architecture and engineering were an icon of New York City, NY. WTC was a site of international commerce and truly represented the power and importance of America in the global world (the entire political, economic, social, and technological world environment). The history of the two buildings (the tallest in the world when they were completed in 1976), allows everyone everywhere to know that from conception to funding to use as a space through which millions passed every year that America has been a place with selfless heroics and many opportunities for people to fulfill their dreams.

More Info: en.wikipedia.org