Wall Street is a term commonly used to encompass the financial industry of the United States, specifically the Stock Market. Wall Street is also the name of a street in New York City. Today, it serves as home base for various stock exchanges and investment, security and brokerage firms. Wall Street is also a collective label for the financial district of New York City. CISCO: Glossary of Financial Terms (2008)

Wall street got its name in a non-financial way:

Dutch colonists settling in lower Manhattan decided to construct a wooden barrier in 1653 to protect themselves from enemies, namely the British and Indians. PBS: Selected Wall Street Chronology (October 21, 2004) In the early 1700s, the British defeated the colonists despite the wall. They built a street in the wall's place, as a symbol of their victory. They named that street Wall Street and the name has not been changed. PBS: Selected Wall Street Chronology (October 21, 2004)

Wall Street began to gain its reputation in 1792:

In March of 1792, two dozen of New York City's most successful merchants secretly gathered to contrive methods for bringing order to the securities business. They also contrived to draw this money loaning trade away from the auctioneers of the city, who were the merchants' competitors. On May 17, 1792, a document called the Buttonwood Agreement was signed by all these merchants. It was named after the buttonwood tree where they traditionally gathered. The Buttonwood Agreement was that these merchants would trade securities only with each other. This way they could set their own trading fees, and shut out the auctioneers. These two dozen men founded the New York Stock Exchange. The address of the NYSE is 11 Wall Street.http://www.hermes-press.com/wshist1.htm

• 1829: Reaches trading rate of 5,000 shares a day PBS: Selected Wall Street Chronology (October 21, 2004)
• 1844: Telegraph is utilized to transmit market quotes PBS: Selected Wall Street Chronology (October 21, 2004)
• 1878: Installation of telephone on NYSE trading floor PBS: Selected Wall Street Chronology (October 21, 2004)
• 1886: Trading reaches one million in share PBS: Selected Wall Street Chronology (October 21, 2004)
• 1943: Women are allowed onto NYSE trading floor PBS: Selected Wall Street Chronology (October 21, 2004)
• 1962: 17 million Americans own stock PBS: Selected Wall Street Chronology (October 21, 2004)
• 1999: Dow Jones industrial average passes 10,000 points PBS: Selected Wall Street Chronology (October 21, 2004)